I don't fully agree either. While a 5 cell is safer, a 4 cell will work, aslong as it is fully charged. Most receivers brownout below 3.5 volts, and if your'e battery is that low, then it's not exactly charged... Especially since the servos probably won't put too much voltage drop. IMO, more than 3-4 flights on a 700 mah battery is pushing it. On my 2000 mah nimh, I always topped it off after 6 flights or less. On my life, I top it off every 3 flights if I have another plane to fly in the meantime, since they are much quicker to charge.

Having said that, the 2000 mah 5 cell nimh is the better choice.

Hubert