You can't go by voltage measurements for LiFe. The discharge curve is so flat and drops off so fast when they are down that you don't get much warning that way. A load test can tell you if a pack has gone bad before your flight, but the only reliable method for knowing how many flights you can do is to calculate your average current use per flight and do some math.
On using an LiFe for a transmitter pack, here's the reality. NiCd/Nimh batteries come off the charger at 1.4 volts per cell. So for an 8 cell pack that will be rated at 9.6v, that's 11.2 volts. That will drop fairly quickly to about 10.5 then gradually down to 8.8ish before dropping off quickly. A 3 cell LiFe rated at 9.9 volts comes hot off the charger at 10.8 volts and gradually drops off until it crashes hard at 9v. So the LiFe, even though the nominal voltage rating is a little higher, actually matches the voltage delivered to your radio perfectly compared to the NiCd it was designed for. it's a similar situation for receiver packs. A 2 cell LiFe practically matches the voltage of a 5 cell NiCd pack.