ORIGINAL: Sport_Pilot
I don't know about that, but they have better batteries so that is what you may have noticed.
Consider that the standard TX pack used to be the 9.6 volt 8-cell pack. Many 2.4 radios use 4 or 5 cell NiMH or 2S lithium packs. Overall I think the technology behind the electronics is allowing for lower voltages to be used.