[FrankJ]

Bomb Squad's swerve drive (4 wheel) didn't seem to have any problem getting over the bumps in 2012. Our kitbox 4 wheel drive didn't have a issue in 2010. That was with one motor per side. As said earlier, it is about ground clearance & design.

Calculating which drive system has the most friction is difficult. You have to have a model of the wheel carpet interface. Classical friction theory says they are all the same, but that model really doesn't apply completely. If you are running a drop center scheme you mostly have traction on just 4 wheels at a time. Welcome to the difference between science & engineering.