I have used a LIFE battery pack with several Futaba servos, but not the 3305. There are some NiMH batteries, though being high capacity packs, that don't supply the amperage a high torque servo will need. Most servos rated for 6V packs do fine with a LIFE. You may want to look at the switches you use, some that are fine for standard servos may be a bottle neck for a higher amperage set up.