I think an RP cost would be great. That, and/or add an exp multiplier for playing a class for a longer duration. It would give some tactical thoughts before the battle. "Alright, we're fighting Orks, so we're going to need a lot of ranged firepower to mow them down before they overwhelm us." While the Orks are thinking, "Boyz, be da biggest Ork you can! Wear lotsa blue. WAAAGH!!!" Then, the Orks overwhelm the Space Marines (woo!). So, now the Space Marines have to make a choice. Lose to the Orks because the plan of having a strong ranged presence didn't work, or pay in exp and RP to change to more melee oriented classes because the Orks are on top of them. Basically, I want there to be consequence when a plan fails. That would feel more Warhammer-like to me, and less CoD-like. I want this game to be brutal, well-thought out plans, and team coordination. I also feel like this would add to the Eldar gameplay in general, since they have specialized classes rather than all-around classes. It would also reward the leaders of a faction, because their plans are crucial. Not that I want the council to dictate how I play my game, but I want the incentive of listening to them to be there.