In last COOP we used helicopters for trasport APC not only personell.
APC was used for support infantry immideatelly after releasing it close to hot area.
You can see rearming APC at enemy artillery battery after it spend all ammo.
I like ARMA2 more and more. There is big advantages in compare with many other games that ARMA has opportunity to interaction between different kind forces (infantry, artillery, navy, air forces etc).
We can create coop missions which will have general line - mission will not can be comleted without help/interaction of each other. For example in case wounding we should to transport a soldier by heli (like in real) or at least to call medical hely for "healing to 100%" so it woild be interesting to remove player death - leave only heavy wounding, so he cant to take part in the action. We will drag him to safe place for heli landing and marked that place by color smoke others will cover.
There is millions of scenarios... we can point by laser some of targets for bombing - for recon group it will takes time to go close to target, find a good position etc etc.. also this group can suppress any AAA defence before air strike. Or infantry gruop can coordinate artillery strike.
I think general rule - remove any boots from our side
