I bought 20 100AMP forward 80AMP reverse servos from RCSmart in HongKong. Use three of them in a PT boat application with three speed 600 BB motors and three 12v10000Amh batteries (DCell). ESCs have worked reliably and with very little heating. ESCs cost $20 each if you bought 10. I have been happy with the purchase. I can go fast but at low cost. NmH Batteries, however, cost about $119 each. Boat weighs in at about 28lbs due to battery weight but still goes very fast