FWIW -and quite some years later- my recent LiFePO4/LFP experiences gained during an extensive EU family outing were
very positive. Our assorted LFP AA/AAA battery powered flashlights, shavers, cameras, instruments, radio gear etc performed brilliantly.As significant travel was via EU's infamous no frills airlines,weight & bulk were trimmed by ditching the usual NiMH cells,cussed mains adapters & chargers to use LFP 14500/10440 types instead. Most recharging was via a 2 finger sized
'Soshine" USB smart charger,which was both a compact sweetie and rapid in action. USB sockets globally now abound on even plane seat backs & hotel PCs/TVs etc, & no qualms arose from picky airline security over spare charged cells.
N.B. The rapid charging feature of LFP can be particularly valuable when on the run. Being able to top up in a hurry from a small charger is a life saver - 500mA at 3.6V takes only ~90 mins to store into a ~700mAh 3.2V LFP, whereas the same current into a ~2000mAh 1.2V NiMH would take >4 hours to stash away much same usable energy. Your appliance would probably need multiple NiMH cells as well.
I'd sourced all gear cheaply pre trip via FastTech in Hong Kong, but - probably as a result of a heads up LFP article in the June 2013 "Silicon Chip"- Australian outlet Jaycar (at least) is now also considering stocking them. However it'd be hard to match FastTech's dirt cheap prices & globally free posting!
As lithium batteries look on a real roll,any other user feedback (both +/-) may hence be worth posting to build up the AA/14500 (14mm x 50mm) knowledge base.
Footnote:Although less energetic than similar Li-Cobalt(Li-ion) types, the steady 3.2V output of LFP (+ a simple series place holding dummy cell) nicely matches the voltage of 2 x fresh alkaline AAs of course. Li-cobalt (Li-ion) deliver 3.7V per cell, which may overdrive many consumer devices, even if dummy cells are used! I'm not LFP biased, but they certainly look inherently much safer and more abuse tolerant than Li-ion/Li-poly,with far greater recharge ability (~1000s versus mere 100s for Li-ion).
Stan.