I don't think I have ever lost more than 500 feet in a stall from the moment I first tried it. But would I do stalling at 1,000ft AGL? I'd rather have a little bit more distance to play with, most places you can climb to 3,000ft while getting to the training area so it doesn't really take much extra time. Nowadays I know I can recover with minimal height loss but I still wouldn't do them any lower than I had to.
Ag training is a different kettle of fish as we all know but general training, why not give yourself some wiggle room?