You're right about 350ma being marginal. IIRC they are packaged as 2/3AAA cells. I can get 2 or 3 flights per pack driving 2, 3 or even 4 mini / micro servos. I've learned to only charge them on the over night rate at home, they don't tolerate field charging too well. The weight and size of these packs is too alluring for me not to use them for the little planes...but you really need to watch them like a hawk.
My only 2.4 radio is a Spektrum parkflyer job...so it's possible that the RX isn't as thirsty as a standard RX..?