I ran mine for months in my revo geared for 43 with a 10xl and it never gave me any problems. I had a fan on it and it never gave me any heat problems either.
The only way it is really going to work well is if you A- Don't run the internal LVC, and B- don't run motor brakes. Brian is right, those voltage spikes are big. That being said, I routinely run my MM's on 6s all the time, no problems. I just use mechanical brakes and don't use the LVC.