For the more sedate "in between fights" on the predominantly heavy focused events, a pure rammer isn't a problem.

For the feather champs, it can be.

Wheels, amount or size. It's the "softness" and contactsurface on the floor that counts, not the amount of wheels used.

But 6 driven wheels have the disadvantage demanding even more power to make tight corners or spin on the spot than a 4 driven wheel machine.