I also use LiFe batteries with my Rx. Love them. You can get balance plug extensions, so that helps keep the battery in the plane. There is a bunch of info. here. http://www.hangtimes.com/ Also Futaba makes a device to check available power in a LiFe. http://www.futaba-rc.com/accessories/futm4166.html BR-3000 There is also a ton of threads on the subject.

Hope this helps a bit.

Just tried the Futaba link, and it didn't work. Just go to Futaba's website, and look for the BR-3000.