Interesting..
The timing on the hobbywing esc could be higher than you had it on the MMM, that would certainly make the motor run hotter, but a different esc wouldnt make the motor run hotter, all thnings being equal (if anything the esc would run hotter). I would look at the timing/ start power/ punch or switching frequencies on the esc, assuming those are adjustable. Gearing up would be the next logical thing to try after that to see if it makes a difference- or gear down even, try everything...
