as much as i was hoping to like ace servos,my feelings are mixed.my 1313 blew because of a sticking carb,poor little servo killed itself trying too hard.my 1015 just died from a real hard daytone rub on a brick wall,servo saver must be sticking or too tight...whatever,its dead.it was a hard hit so im not really surprised.both servos performance was great however.i also have heard great things about them,but heard also lousy customer service.
as for the voltage,from what i understand is that lipos tend to have voltage spikes for whatever reason.imo a servo MAY have fair life 7.2 volts from nimh,but the spikes from a lipo might be too much for the electronics inside?dunno.just another angle to look at it from.