I'm sure you're all tired of Grey Knight stuff right (I know BroLo is!)? Let's move laterally then and discuss Marines in general. Today a bunch of us got together for a skype chat (BroLo finally believed I do not have an Australian accent) and after BroLo left we could actually discuss something of importance. If I recall there was TheKingElessar, Sageofthetimes, Archnomad (though I don't think he was listening) and Goatboy. Not to mention myself. So what did this great gathering of nerds do other than make nerdy jokes and talk about painting? We of course discussed Grey Knights and how henchmen (specifically the passback style squad) and Coteaz fit into the grand scheme of things. I'm sure most of you have figured out by now I'm a huge fan of Coteaz*** (if you are an amazing converter/modeller and love Wheel of Time, skip to the bottom and read this foot note) and the options he opens up for Grey Knight armies. However, whilst Coteaz brings more bodies to the table for a very elite army, those bodies are rarely durable (particularly MSU style squads in vehicles) and therefore not reliable scoring. This led the discussion to MSU based Marine armies (i.e. Razorspam) and the general dislike against their reliability. I'm going to put that discussion onto paper which looks at the differences between large and small Marine squads and their relative pros and cons. Right here.
N.B. I started this post over a week ago so the time frame of the above paragraph is off. Live with it.
In the broadest of senses we are comparing small 5-man Marine Troops in Razorbacks/Rhinos compared to larger 10-man Marine Troops in Rhinos/on foot. Specifically scoring squads. This includes all types, Grey Knights, Grey Hunters, Tacticals, Chaos Space Marines + cults, Assault Marines, etc. (are there any more?). There are pros and cons to both and like many things in life, a compromise between the two will often yield the best results but let's look at this in more detail.
MSU - Multiple Small Units
Pros
The smaller squad is often part of a concept called MSU or multiple small units. What this looks to do is minimise the cost of a unit to effectively take more of them whilst still significantly impacting the battlefield. This allows the controlling player to maximise their usage of the force organisation chart (by filling it to the brim) which ultimately provides a lot of targets for your opponent to deal with. By taking more units who have access to transports which can impact upon the game, you are able to get more of those tanks (the 1+1 concept, army within an army, etc.) and therefore have an army capable of doing more damage. Whilst these targets are quite often fragile in the grand scheme of things, it offers up unprecedented flexibility to the controlling player and maximum fire potential. By having more units than the opponent, it is a lot easier to create wide spread suppression fire, limit wastage of shots and be very hard to tie down effectively. A unit is lost from MSU based armies and the army as a whole just continues trucking along. This all sounds really good but let's hark back to the 'small' aspect of the unit.
The common theme of all of MSU units is they are relatively cheap (<190 points), spammable and consist of very few squad members. We've covered the relative pros of using such builds above but didn't really touch on the major con of doing such: minimal bodies. Now in many MSU based lists you may have the same or similar number of bodies in a non-based MSU army from a similar codex just spread over many more units. Why is this bad?
Cons
Two reasons. Units are a lot easier to eliminate and units have less offensive punch. Pretty easy to understand when the units are smaller obviously! Now, mathematically speaking this isn't true as it's going to take the same number of wounds to kill 10 Marines whether or not they are in one squad, two squads or ten squads (unless we get into wound allocation shenanigans but suffice to say you need to inflict 30 wounds to force 10 failed 3+ armor saves). You need X amount of wounds to inflict Y failed saves. The same number of Marines are going to put out the same number of attacks (in fact, they put out a bit more with multiple Sergeants), etc. Simple but not so in reality. Remember also that two MSU squads =/= the same point cost as a single larger squad. Whilst we are gaining more from our FoC and all that it entails, we are paying for it. However, let us look at some of the minute differences between two times five man squads and a single 10 man squad. We'll look at durability first.
It is a lot easier to saturate a target with wounds when there are only five members compared to 10. This makes it easier to kill specials/leaders which in conjunction with the smaller squad sizes, makes smaller squads more likely to flee (easier to force morale checks and less likely to have higher Ld bonuses). This statistically isn't huge but in-game, that extra bit of reliability lost is often the difference between holding an objective or not. Overall though you are more likely to take more Ld checks and those extra few fails will crop up at times. At the same time, those smaller squads are also protected by individual hulls which makes exposing those 10 Marines more difficult than in a single, larger squad.
And this brings us to offensive capabilities. With the army within an army concept in mind, MSU based squads can be more offensively potent than larger squads as they have access to more transports with heavy weapons. The insides however, well that's a different story. When MSU works perfectly, offensive applicability isn't an issue. Bringing to bear lots of smaller squads to focus fire/combat a target works just as well as a larger squad and this is often a good principle (BA Razorspam, Jumpers, etc.). However, because there are more squads involved this is harder to achieve. It is easier for squads to get bogged down, wiped out, forced to flee, blocked, etc. If you can bring all of the small squads to a single point of attack at any given time, this tactic can overcome their individual offensive weaknesses but isn't always possible. Certain MSU units do this better however such as five-man Jumper squads (12" move) or units which are looking to torrent shoot rather than torrent assault (i.e. GKs with Stormbolters).
Again, the end result in terms of offensive output is similar between a couple large squads and multiple smaller squads but in terms of applicability and individual effectiveness, the smaller squads aren't quite as effective but simultaneously are capable of doing more damage as they can target more units and limits the chances of overkill.
Full squads
In comparison to MSU based squads, larger squads counter all the cons but don't have their strengths. Shocking. Larger squads are more durable and therefore reliable and more offensively efficient (particularly in books with unlocks at ten-strong only. Hi Vanilla Marines). This efficiency is a lot easier to apply as only one unit needs to move to an area but at the same time is easier to block, delay, tarpit, etc. On the flipside, the units are more expensive, there are less of them which weakens offensive potential (spread of fire) and the army isn't maxing out the FOC or taking full advantage of such concepts as 1+1/army within an army, etc. All that being said, large squads are very effective in midfield because of their increased durability/efficiency. Demanding an opponent remove three ten-man squads of Marine statlines is a pretty tall order, particularly since they are all effective at close range and many are effective in combat (poor Tacticals). Demanding an opponent remove six five-man squads of Marines is also a tall order but a less daunting task as outlined above.
In the end, this is why you take larger squads. They are far more reliable and therefore much better objective holders. There are other benefits however. Larger squads are generally more threatening to your opponent not the least because they are harder to remove but are more damaging to a wider range of targets. For the most part, MSU units aren't threatening by themselves to every aspect of an opponent's army. Certainly five ASM or five GH + a Wolf Guard are pretty good in assault for five-six guys and their special weapon options (generally melta-type guns) give them great ability against tanks and is often a basis for MSU armies. However, without a lot of these squads in a localised area (and we've already discussed how this is an issue), they just aren't scary to an opponent. Certainly two melta-type weapons per unit is a huge deterrent for vehicles but in terms of holding midfield, larger squads are just better at it. They are scary to both tanks and infantry alike. MSU units need to work together to generate this type of effect but again, this is more easily disrupted as discussed above.
Conclusion
Obviously this isn't to say smaller units are bad, they are just different and this is what this post is addressing. There is an obvious trade-off between having lots of smaller units and accessing their transport option compared to take less larger units.
The army with lots of smaller units is way more flexible and can cover more of the board, take more objectives, threaten more units, generate better suppression, generate better kill ratios, etc. The trade-off? Those units have to work together to be effective in combat or anti-infantry shooting and because there are multiple units, disrupting that synergy is easier than eliminating a single larger squad. At the same time you are paying more points per model as you are buying those extra tanks to cart your smaller squads around. This gives you another vehicle and depending upon the vehicle, more heavy weapons but it obviously costs more points. This vehicle can also up your survivability as your opponent has to break open more transports to access the Marines inside but also forces more Ld checks and means the units are easier to isolate.
On the other hand, armies with lots of larger units are less flexible. There are less units on the table which reduces the ability for the army to capture multiple objectives (though large squads can string out), not waste firepower, suppress multiple targets, etc. The trade-off? Your units are hard to remove. Ten MEQs are pretty dang durable and there's no way to deal with them five at a time. This means your midfield is a lot more secure and a lot more dangerous to your opponent as those ten man units can put the hurt out on many squads (assault those ten Grey Hunters, go on) both in assault and through shooting.
One thing we didn't discuss is many of the MEQ armies are also able to split their large squads into two smaller squads via Combat Squadding. This can give the larger squads some great flexibility in certain situations and whilst you don't gain all the advantages of the MSU type squads (you don't get two tanks for the squad!) it is an excellent option for spreading fire power and ensuring efficiency but with the associated costs.
In the end I think a lot of people focus on one style of squad over the other. This is fine and lists can be built around these concepts and do well. At the same time I think combining them gives you the best of both worlds whilst covering off each other's weaknesses. Add in the ability of some Marine armies to combat squad and taking large and small squads can create a very flexible fighting force.
*** Right. Coteaz and Wheel of Time. I had a crazy idea and it can so work okay? Coteaz = Perrin. Purifiers = Aiel. Purgation/Psyfledreads = Two Rivers Bowmen. Henchmen = wannabe rabble. Interceptors = Winged Guard. Rhinos = travelling. Assortment of HQs = 'council' such as Ash'man, Aes Sedai, Faile, etc. Amirite or amirite? Aka plain stupid =D.
