Guys the Antigravitys are awesome! I am now a dealer for them and have a few weeks and 20+ gallons on mine and love it. It is not even fair to compare the two. I have a few in stock and can get anything you need. These appear to be THE answer.
As far as chargers, go here:
http://www.progressiverc.com/chargers/battery-chargers
Great service, price, and the best chargers on the market.
Tyrant, be careful....LIFEPO4 batteries will stay at 13.2 right up until they "fall off a cliff", or deeply discharge. The only way to know the state of charge is to measure mAh when recharging. Ride a tank or two, recharge with a proper charger, divide mah by two, and determine use per ride................This is the same way they are used in RC applications. You cannot use voltage to check them, as they are 13.2 right up until they are dead.
Please let me know if you guys have questions. Not only am I a dealer but I have been using them in RC applications for the past several years........................