To tell the truth, I haven't ever "run out" of Tx power even with the 700mAh packs. Maybe that's because I'm using a pretty basic radio that doesn't have a lot of bells and whistles...that I don't attend all-day fly-ins or competitions. My Rx batteries always run low before the Tx batteries...and both last for at least an hour in the air and that's the most I'm ever likely to fly on one day. I think once I did a "flight marathon" with two models and put in two hours in the air during perhaps three hours at the field. It was exhausting!

If I could find the Sanwa 700mAh packs and they were cheaper than the packs listed on some of these sites, I'd buy them. I've noticed that the newer radios seem to be moving away from these square packs towards flat packs...I suspect there's a little planned obsolescence at work here (like discontinuing the print cartridges for printers that work just fine) in an effort to move us towards buying newer radios.