Interesting stats, but it leaves out one important aspect of the combat system.
Each "round" of combat, each DIVISION involved has a chance to fire... thus having 4 divisions against your enemies 3, gives you a clear advantage.
I've taken it a step further, and created divisions of TWO Combat Brigades, followed by 2 or 3 support Brigades (depending on what tecks I'm working on). Thus having FIVE shots per round as there are 10 frontline 'slots' per province front, and my unit frontage per division is TWO.
This can add to the amount of Brigades involved in the combat... but even 5 divisions of 5 Brigades is only a 25% decrease in combat power.... vice 4 divisions of 5 brigades which would give you a 20% decrease...
I'll take a 20% increase in firepower over a net 5% penalty anyday.
I also often add 2 Combat Brigades to HQ units... it decreases the firepower of that unit... but makes it a very good Second Line unit used to clean up the "leakers" (enemies who manage to retreat back into your lines).
Sorry, but you've misread how the 'shots' work: "Thus having FIVE shots per round as there are 10 frontline 'slots' per province front, and my unit frontage per division is TWO." This isn't correct, you don't get 1 shot per division per round. The number of shots is based on the divisions total soft/hard attack values, from the manual:
"The Firing Phase consists of a
series of Shots, the number of which may vary from hour to hour, depending on the capability of the units involved. These are numbered as “Shot 1,” ... The Firing Phase will continue until there are no more Divisions eligible to fire a Shot in the one-hour Round. ... Each Division has a
number of shots it may be able to fire during a single Firing Phase. This number is largely dependent on its Soft and Hard Attack values, modified by its Effectiveness. It is also lightly affected by random factors. ... Every
round, each Division will randomly select an enemy Division upon which to fire."
On average, low combat width divisions are at a disadvantage versus high combat width divisions in combat,
even when you've got the same total number of identical brigades on each side. This is entirely due to the fact that divisions select a target division for the entire round. The larger division gets
more shots and can exceed the smaller divisions
lower defensiveness/toughness, hence getting guaranteed hits for later shots. The smaller divisions get
less shots and can't exceed their opponents
higher defensiveness/toughness so all of their shots have a chance to miss. The high width divisions, even when attacked by multiple low width divisions, receive a smaller percentage of total shots as guaranteed hits.
A good case to consider is 2 divisions of 2xinf versus 1 division of 4xinf, where the 4xinf division always concentrates it's firepower on one division of 2xinf, overwhelming it's defensiveness/toughness whereas the 2 2xinf divisions combined can't overwhelm the 4xinf's defensiveness/toughness. It's the guaranteed hits versus the (80%?) chance to miss that make all the difference. The greater the disparity between width on each side, the worse this effect becomes.
Personally I think this is a major flaw, since attacking divisions aren't even going to know exactly where the defending divisions boundaries are anyhow, so concentrating all of their firepower onto just one division is unrealistic. But that's the game mechanic and we're probably stuck with it
Obviously, you can improve the odds by packing in more support brigades, but that's avoiding the point of a like-for-like comparison in total composition. It's also heading towards the realm of gamey mega-stacks