ORIGINAL: PipeMajor
Actually I don't think you're that far off. The TX w/FSS modules seems to do pretty good. Someone on the Futaba support forum quoted the synthesized R319DPS RX has a drain of 40mAH vs. 10mAH for a crystal controlled R127DF or 13mAH for the R138DP RX. The overall drain of the entire flight pack is likely not that great a difference since the servos would obviously be the biggest contributing factor. With modern PCM synthesized gear and many more digital servos in today's models, the stock 600/700mAH NiCD packs are ridiculously undersized.
I was the one that quoted that. The current figures are posted on Tower's website in the notes for each receiver. A little bit of math and you can easily conclude that the FSS module will reduce the flight time of the stock 700MA battery by only about 10 minutes on average. 40ma is nothing compared to the current draw of 7 servos in my Ultra Sport 40.