I agree that cam-based bots aught to be given a small weight advantage (I think you suggested 25%?)

ANY walker, even cam-driven, immediately suffers from half-speed compared with the same motion applied as wheels. (Because a foot must move back and forwards to produce one forward motion) not including other losses in efficiency from the mechanism. Anarchy has a top speed of 5mph.

The weight allowance is there to compensate walkers somewhat and encourage people to build them. So you don't immediately change the rules the second that someone manages to build one that isn't a complete waste of time.

I personally have no problem with the idea that full weight allowance requires separate motion in 2 axis (min) though.