I don't know what M2TW will be like, but powder will likely be a battle-winner par excellence based on its effects to morale.

With bows in MTW, one enjoyed the same casualty rate as mid-grade powder units. However, the difference was that, with powder units, the enemy loses 5, 10, 15 men at the same instant after a volley is fired. I remember this as a rout-inducer by itself in MTW, even without the additional cavalry-fright effect, and I would guess (just a guess, of course) that M2TW will be similar.