People DO run the CC 2200 on 6s, but those who do say it is insane power. Diffs won't last too long, especially traxxas diffs. I personally think the 2200 motor is a better 4-5s motor for MT/truggies, while the 2650 is a better buggy motor on 4s. I tend to like rpms between 37k and 45k and just gear down. The higher rpms/lower gearing reduces chances of cogging.