True, you can use 'Tumble' or 'Lunge' to move passed people, however, if both of those skills are not available, and let's say you're in BOSS Mode (especially,) and you want that last shot or w/e in on enemy, but you cannot get to that enemy, it's a little nerve wracking after a while. I also find it hard to take down certain enemies while with allies for the very fact only so many can attack at once on a BOSS or regular enemies. I think your game is quite elaborate already with some complex and interesting systems, and doesn't cause any lag thus far. If this system you were to produce was made well, there is no reason it would lag. It comes down to whether you want to implement it or not. This system would be an all-the-time 'Lunge' and 'Tumble' effect for allies with other allies during regular walking or running around.