We had a battle-bot competition at my college for an engineering class- We used two of these for a 30lb. bot and it had much more power than we needed. The motors worked flawlessly, and helped us with the competition.
It has way more than enough power to drive my 11-kg bot. I'm quite pleased with it!
This motor has very low backlash and gobs of torque. I used it to operate the steering on a 3 wheel car, and it worked very well. Very responsive!