This is probably not the answer you want but I'm learning to fly this for the first time (coming from coax) and all I'm doing is trying to do a steady tail-in hover in a tight 10x10 room while keeping it in a 5x5 area without crashing. Whenever I feel like I start to lose it, I put it down pretty quickly.
Doing nothing but this a battery last me 20-30 mins as the clock would show, but this includes moving re-setting, dinking with trim settings etc. At most, I've kept it up for about 2 mins without putting it down.
Not sure how long the flight time would be if it was airborne the whole time, but I'd imagine at least 10 mins.