I have the 2650 in my 8ight. I didn't have my temp gun w/ me but after a full run doing wide open speed passes on a 5s 3900mAh pack I was able to hold my hand on the motor without pain indefinately. Gearing was 12/46.
The 2200 should run very cool on 5s, but like everyone has said, it will be too much for racing and better for bashing.
Check out my custom converted 8ight:
Sub 7lb, lowest CG of any 1/8 buggy