RE: I need your honest opinion.
The decision to go with A123 batteries is a good one. I used NiMh batteries for about 2 years, and they worked well......until I let a couple of battery packs sit unused in my shop for several months. NiMh batteries need to be regularly charged and cycled and not left sitting unused. A123 batteries don't have this shelf-life problem. A fully charged 2S A123 battery will put out about 7 volts and I was worried that I would need a voltage regulator. No problem. I and many others use 2S A123 receiver packs without a regulator, and they work just fine. I've been flying Futaba 2.4 FASST radios for almost 4 years, and I run all digital servos. In my opinion, 2.4 GHz radios are the best and most reliable radios we have ever had, and A123 batteries are the best receiver batteries (airborne packs) available.
Best Regards and Happy Flying
JC (FASSTFLIER) AMA3240