2-cell LiPo batteries are fairly inexpensive and very light weight. They allow you to run your receiver and servos at 6v (with a regulator) at a considerable weight savings versus a comparable NiCd or NiMH pack. LiPo batteries also have a much lower rate of self-discharge when compared to NiMH batteries.

It would be a simple matter to fly a typical .40 to .60 sized sport plane with a 2200Mah 7.4v LiPo for a receiver battery and enjoy several benefits. The LiPo battery would provide maximum torque and speed from the servos when used with a 6v voltage regulator without adding weight to the plane. It would also allow you to fly ten or twelve flights without needing to recharge instead of the typical 3 or 4 flights you'd get out of a 600Mah NiCd receiver battery. You could also charge your plane and put it away, then be assured that the battery is still fully charged the next week when you pulled it out to go flying.

I think LiPo-powered receivers will be more and more common as prices continue to improve. The average sport pilot may not need the power and longevity that LiPos provide, but I'd think most pattern or IMAC pilots would jump at the new technology. The pattern pilots at my club practice and practice and practice all the time; for that kind of flying, the extended run time that LiPos can provide for high current servos is simply one less thing to have to worry about. Being able to provide extended servo power while maintaining or even reducing weight is simply an added bonus.