As a combat veteran I add some realism to my campaign. One rule I have adapted that is both realist and helps the players a bit is what is known as fire teams. In reality a squad will have a leader yes, but there is a hierachy for what if that one falls? and the next? What if the squad needs to split up? So you have fire teams, groups of 2-3 members of a squad that work together for a specific task. How this translates into the game is instead of only allowing Squad mode for the entire squad you can break it up. Maybe a tacticle marine is up on a hill with a spotter sniping while the devestator is under them at the bottle neck, and the assualt marines and chaplain are holding ground up ahead. You can break them up and have them in seperate modes that benefit thier individual situation, the down side would be cohesion of the fireteam leader is probably alot less then the Ultramarine squadleader or what have you. There are a few ways you can translate this into game terms but just wanted to put out that idea to some of you that hadn't considered it.