I know it's old, but if you haven't resolved it, I'd suggest calling Himoto about the receiver issues. I've dealt with them some, and it's been surprisingly pleasant. They have been very helpful and we've now got 3 more of these running identical setups with:

1) the 2200mah 40-80C batteries from HK
2) Himoto Heat Sinks
3) Himoto Aluminum Motor Mounts

Mostly we race on the street, dirt, and short grass, but my immediate neighbor has very deep bermuda grass (as deep as the top of the truck, it almost disappears other than the rooster-tail of grass). Against my suggestions he's run his around his front yard for multiple minutes straight, mostly at full throttle. It still did NOT get excessively hot

We are having a BLAST with them