I'm sure you'll get some replies from 9 owners. I met a 9a owner who flys from his own 600 ft. (200 m) strip. He used to fly a 6, but said that the 9a was much more comfortable to land there. I'm not sure that I'd ever be comfortable on a 600 ft. strip, but I think with practice 400m would be no problem, especially if it is unobstructed.