People worry that the LiFe is too much voltage going from 6v to 6.6v, but if you look at the actual discharge curves of them and a NiCd you'll find that the voltages are very close to each other in actual application. I checked mine and found that the LiFe was only .2 volts higher than the NiCd at the receiver when fully charged, and fell in line with a hot off the charger NiCd fairly soon in use. Essentially, an LiFe battery gives you the power of a fully charged NiCd all the way through its practical discharge range. The only negative I've found is that you do have to buy a charger that's made for LiFe batteries, and you do have to use the balancing plug to charge them. That's a small issue if you have the battery in an inconvenient location for balance reasons, but nothing a little extra wire and some solder can't fix.