[MrForbes]

If you're going to get into robot pushing matches, then you need a more powerful motor controller. But for just driving around, the 12 amp controller should be fine....as long as you don't have a long skid steer robot. Using two drive wheels, and caster(s) to keep it balanced, should make it so you don't work the motors and speed controllers very hard.

Those little motors will smoke if you try to work them too hard. Having a speed controller that will cut off like the BB ones will, could be a good thing.