the fact that we had our drive wheels mounted in the middle really kinda negated any effect that ramming us in the corner might have. last year we did have omni wheels in front and drive wheels in back, but since our turret could spin in any direction quickly it wasn't really an issue.
we decided to go with six wheels this year, and that gave us the same kind of instantaneous reaction we needed. if we got hit in the corner we could turn almost instantly instead of having to swing our front end around. also, since the drive wheels are in the middle, their traction is evenly distributed. if someone hits you in any corner, alot of the impact is taken by the drive wheels, no matter which corner it is.
it really is an awesome drive train, turns literally on a dime, and it's super fun to drive (although i think it'd be even more fun to drive one of the sparky triplets with those mecanum wheels
)