Since I got my Scorpion HK2221-08v2 motor and the Scorpion Commander 45A ESC that went with it, I have run into this issue where the ESC seemed to cut-off after a minute or two of pitch pumping 3D moves (like tic-tocs).  The ESC puts the motor on very low rpm (not a full cut-off though) for like couple of seconds, after that the headspeed recovers.  The ESC was very hot.  I crashed once (mild crash), and was able to recover safely in two other occassions.

I had noticed that it is recommended that the ESC be fixed outside the canopy, which is how I had done it initially itself.  So I contacted Innov8tive Designs (the distributor of Scorpion in the US), and Luciene Miller responded.  I was wondering if the 13T pinion was the problem.  But Luciene confirmed that 13T is fine on this setup.  Instead, I was asked to check if there was at least some airflow on the back-side of the ESC (the side without the heat-sink).  Sure enough, I had put a big strip of double-sided tape there, and there was no airflow.  So I removed the double sided tape, and just attached the ESC with two small strips velcro on two ends of the ESC, and secured the whole thing with another long velcro strap to the frame.

I have been able to do full packs worth of 3D after this change.  Thank you Luciene for the tip, that the backside of the ESC contains the BEC voltage regulator chips which generate a lot of heat. 

Here are couple of pictures, to show the gap between the frame and the back side of the ESC.