I purchased the Losi 1700kv combo kit, it's not bad. ESC program can use a little more work (imo). It's not as sooth as MMM when braking, over all I'm pretty satisfied with the setup. I do know a person who has the 2100kv kit, he is experiencing cogging issues, but only when the lipo is getting close to it's cut off setting. Also during this time the motor jumps from 130 to 170+, but ESC stays at 110F - 120F, lipo doesn't get pass 110.