What do you want with these questions? "Oh, to be considered a successful MTT player, the minimum ROI% is 10%." You need to (IMO) find out how much ROI you WANT to make, and go for it.

NOTHING in poker is absolute. I'm sure you know this. If you're trying to guage how good you are with other players' returns, you're going to either set your standards too high or too low. Find out what you want to achieve, and work until you do. Good luck.