jester_s1

If the manufacturer rates it for 6v, that means the voltage of a 6v NiCd. That comes 7.2v hot off the charger with no load. Lipo and Li-ion will go to 8.4 and 8.2, which is too high unless Futaba approves it. A 2 cell Life is only 7.4v at full charge, so it will be safe.
On the regulator, it's never a good idea to use one unless you have to since it introduces another failure point in the system. With good Life's on the market, there's no reason to go that route anyway.