All this talk about the MMM "not holding back the amps" is cracking me up.
Guys, you dont want an ESC to hold back. That makes it less efficient. It's true the MMM uses FETs with a much lower resistance than the MM does. Therefore the motor will draw more power. I think it's impossible that a controller can outright ruin a motor unless there is a problem with the programming that makes it cog like hell. Which you would obviously notice BEFORE it fried your motor and you would stop driving.....
Definitely make sure the motor screws aren't too long. That has been a common problem around here with the Feigaos. If all is well then just face the fact that Feigaos are cheap and if you overload them they will get really hot and fail. Done. The MMM is not at fault here.