I got tired of the short battery life of my DX6, and I didn't want to risk doing the voltage regulator mod, or use a LiPo, so I bought one of these. Drop-in replacement, problem solved! The Sanyo cells are great, they hardly lose any charge overnight. And this pack has about quadruple the capacity of the stock pack. I charged it to 10.9V (using the stock charger) and then left the radio on for a while to test it...after 4 hours and 40 minutes, it had only gone down to 10.1V. Heck, that would have been about three full cycles on the old battery.
I flew with it today for the first time. It had been a few days since I charged it up...but I didn't even worry about topping off the charge before I left home like I always used to do with the old battery. With about an hour of flying use at the field, it went from 10.7V to 10.4V.