I'm currently using both of the Intellect Life batteries and I can honestly say that I'm sold on them. I thought moving up from a 9.6V NiMh wouldn't have been that much of a ROF gain but the LIFE batteries with the extra .3v makes an insane difference.
I've gamed them both in my M4 and Mp5 with full stocks as I was looking to gain some space after installing the ASCU on both. I did have to knock out the tabs in the stock to fit both the stick LIFE and ASCU but if you don't run a mosfet or any type of a controller, it should fit fine, or just get the tri-panel version.
I have a little problem fitting the stick into my AK spetsnaz but I will figure it out by the next game.