It would be better to use a Kontronik 55-10-32 instead of the 40-10-24. In Germany, many people use it without problems at peaks of 2,8kw on 10s Lipo in their Helicopters. I have also ordered one yesterday, look at the threads of othello, it works great.
The voltage on 8s Lipo should be no problem, some guys here in Germany use their Jazz 70 on 4s Lipo instead of 13v maxximum voltage and it works perfectly. The only problem could be that the motor draws to many amps when you are accelerating.
Hope this helps, sorry for my bad english