Info seems to be inconsistent and probably due to different designs from various manufacturers.
Also LiFePO4 is so new thus no long term stability report.
One thing that seems to be true is it does not have the same problem as Li-Ion/Li-Po (Li-Cobalt) as it has gas swelling problem -- and dead, when fully depleted.
I've seen one factory recommendation:
do not deplete below 2V and never go below 1.5v (as has potential to shorten the number of recharge cycles/usable life.)