From: Salinas, CA
The engine already allows to perform multidirectional attack, so theoretically you don't have to stack your units.
Also you can attack, witdraw the unit, place there new one and attack again. And again, And again. IIRC the infantry during WW1 was thrown in waves. Usually each one to push the enemy from one (few) line(s) of trenches.
I'm starting to see that by allowing for two different unit sizes that you do this instead of stacking. The more I play SWiE and ToF the more I'm liking this approach. You are correct that units were thrown in in waves, a certain amount of frontage will only support so many men, tanks or artillery to attack or defend that "front" line. Especially in WW1 this wave approach was truly in vogue, lots of piecemeal attacks one after the other day after day.
The one thing about swapping units after making an attack is that you can't use swapping, that uses all AP's for both units and after a unit attacks I doubt it can swap. That means having to make sure that if a unit attacks it will have enough AP to move to an empty hex so another unit can move in with enough AP's to launch it's own attack. A delicate dance that the AI is incapable of unfortunately. Of course one can also attack more than once with the same unit. I like being able to make a combined first attack to really weaken a strong defender, then use strong single units to kill it one attack at a time.
I like the way you did leaders as well, the more I play the more I like how leaders work. I like the way they pump up the unit strength they are in while giving some kind of less obvious advantage to nearby units. I like the way it models how leaders would go to some unit to give them more impetus for attack or defense. I think some do not understand that these leaders don't just represent the actual general or admiral but also the combat assets that their higher level of command enjoys. It's like moving in the Army level assets plus the general staff to give some unit better combat performance. My only beef is why don't air and naval leaders gain experience like ground leaders?
I'd hold pat on how you modeled the lack of stacking. Some players want everything to be too easy, they want to play the biggest-stack-wins game that is just so lame.