Well like I said to each his own, I have been assembling giant scale planes using hitec servos for some time know and i have never had a servo problem due to the use of 6 volt packs, and all I ever used was 6 volt packs. This was with digital and none digital servos.

Hitec has also been rating servos for 4.8 to 6.0 volts way before regulators were so popular so I can't see what the proplems would be unless using lipos which put out over 8 volts fully charged.