If you have any questions about the feather axe-bot (deBiel) you can send me an e-mail. I can tell you that a lack of traction does not prevent the axe from smashing backward and forward. This is simply newton doing its job, the mass of the wheels with the motors providing torque agains the mass of the axe.
I will be competing in the Thialf event on 22-24 June, adding rubber to add traction. I hope it has a dramatic effect, although hopefully not on my speedcontrollers
The forces involved are quite nasty.