Lithium has power/density edge. It's roughly 3x times better than lead/acid but as other people said, it's precision device that doesn't tolerate discharge past certain point. Most Lithium-run devices monitor each cell, temperature and cell voltage.
Thus you might want a Lead/Acid or NiMh battery after all.
Edit:
They seem to sell LiFe chargers as well:
http://www.batterymart.com/p-sho-bms01-shorai-battery-charger.html
(Notice all additional wires used to charge the battery)
If you need power/density and can protect the batry from deep discharger, then it'll work.