How about this idea.
Collisions should only hurt if BOTH planes collide.
For you numties, here is an example.
Let's say you are the one that collides with the guy, but the other guy manages to avoid collision on his computer, the server gets only 1 collision reported and not 2, so then the server says, ignore collision.
Mutual collisions should only hurt.
Sound like a good idea?
I see nothing wrong with it.
(I currently like the way it is now, but maybe this idea will be more acceptable by more people)