Raimund Specht's recorder tests include the 722 and FR-2LE.
http://www.avisoft.com/recordertests.htmHis results show the 722 preamp self-noise at -128dBu, and the FR-2LE at -125 dBu when the preamp is running at full gain. This is a small difference, but audible as slightly less noise when recording a very quiet subject with the 722, and using a mic with very low self-noise. The Sony PCM-D50 produced a -124 dBu result in Specht's tests, the best of the small recorders.
Depending on the subjects you plan to record, a measurement of preamp noise at full gain may or may not be helpful in choosing a recorder. If you're mostly recording loud music, you won't be able to hear the difference.
The 722 and 702 use a Sony-style camcorder battery. The FR-2LE can use an RC car battery mounted internally. Both approaches are good solutions when you need more than 5 hours of continuous recording while providing phantom power to your mics. The D50 runs more than 10 hours on 4 AA cells, but can only provide "Plug-in power" for mics.
Flintstone