Mine came with a 700 MAh pack too.

Manual says radio draws 280 MAh. Now maybe that is max and not continous. Perhap there is a peak and drop based on what you are doing. Based on 280 I would expect about 2-2.5 hours till low voltage signal.

For many people this is plenty.

I have been to glow fields, and those guys seem to take LONG breaks between flights. Over a 3 hour period some of them only take 3-410 minute flights. an agressive flyer may take two flighs an hours. Great generalization, I know, but this is what I have observed.

Electric flyers seem to land and swap packs, set one on the charger and go back up far more frequently. I see them more typically taking 2-4 10 minute flighs an hour. For them it better be a shorter day or get a bigger radio pack.

Thermal glider pilots seem to spend even more time in the air than either electric or wet fuel guys. Launch, hunt, fly or land and launch again.

I fly electrics and thermal gliders - the 700 MAh pack seemed to be OK for me but occasionally I had to recharge the radio at the field to get those last few flights in.

Slope glider pilots seem to get the highest air to ground time of any type of flyer I have seen. When I started flying slope I immediately went to 2000 MAh packs. When one of those failed I went to a 2500 that lasts forever!

So how long things last and what is enough is very much a personal thing and the type of flying you do.