I agree with david. I'm not surprised at all the you have smoked 2 quarks with the setup you mentioned. 14+ lbs is a big truck for a 7xl I agree that You need to run a lower kv motor. A 7XL spinning at 43K rpm on a 14lb truck will pull a hell of a load. Shoot for a total motor RPM on the conservative side to compensate for the extra weight that will be stressing the system. A high RPM system and heavy load are a recipie for disaster IMO.
As far as the MGM goes. If any controller can take that load it would be the MGM. They run coolr than anything else out there by far. If the latest software update for the false overcurrent problem does indeed solve the issues some have been having (including me) then it would be a great controller. I would hang tight and pay attention to
THIS thread before making a decision on the MGM.