I'm a fan of Zippy batteries, I use
http://www.hobbyking.com/hobbyking/stor ... ouse_.htmlin my FlySky TH9X, my low voltage alarm is set for 9.0v even though the nominal is 9.9v, full charge shows 10.2v.
I have only charged the battery once in 3 months, maybe 5 hours operating time allup and showing 9.4v.
I charge using my Accucell 6 by adjusting the cell voltage to 3.3v the charger then recognises the battery as LiFe, Bruce has a vid on this charger for LifePO4 use.
The 9xr allows connection via the balance lead however I would check the polarity connection of any lead being used, if this is like other 9x units reversing polarity is a unit destroyer.That is probably why they recommend not using other LiPo/LiFe packs.