RE: 8611 Voltage
I have been flying 8611's in my BVM KingKat for the last 7 months on two 1800 mah 6 volt packs regulated down to 5.7 volts.
No issues at all. As stated above, Horizon actually has released specs for the 8611 on 6 volts. I am guessing your salesman might be a little missinformed.