I have been using Duralites lithium ion receiver packs for a few years now and have been very impressed with the quality, durability, ease of use, and great performance. Some of the advantages that I see are, increased flight time without charging, constant servo speed, and extremely easy charging.
What I use
Receiver: 2800mah redundant lithium ion pack
5.1v regulator with fail safe switch
Charger Duralite 4 port charger
Volt meter Duralite digital load test meter
It is very important to check your pack voltage before you go fly. Stop fly voltage is 6.9 and you should recharge at that time. Lithium Ion has no memory effect, so you can charge at any time.
Use a 5.1 volt regulator with digital servo’s. You will see better servo life and reliability.
Use the fail safe switch regulator. If the switch fails, you will simply not be able to turn off the heli. It is a cheap safety item. I have personally lots heli’s due to a bad switch for another mfg.
Always check your batteries before every flight. You can spot battery problems quickly if you get into the habit of testing regularly.