I've been running a 7/8" ROH on older Jackson MKIV blades. I've gone up to 15/16" once, and liked it, but it does get a bit screwy stability wise even with waltz jumps. I generally prefer a bit shallow of a hollow, as you get better glide and "flow" I guess. But now that I'm moving onto jumps a little bit, I think I'll be going deeper, probably about to 3/4" or so whenever I get new blades. I tried shallower, because I met another guy who seemed about my weight/height, but was older, and he used 7/8, so I just went up and up, from 1/2", to 9/16", gradually up to 15/16" and stopped there. In general, though, I like it more shallower than most people, and I feel knowing that a shallower ROH and me agree more helped me a bit. Most people I know won't go over 5/8. I know back in "the old days" shallower ROHs were a lot more common, but now people seem to prefer deeper. I think partially it could be due to my weight, I'm a guy and 195lbs, and so I think a shallower hollow suits me better.
So, what radius do people here like using?