I think the most I've gotten was around 4% experience at level 212 within the one hour time limit. I'm worried they're gonna nerf the particular quest though when they find out. Probably with a limit cap on how many times you can do it... presuming of course it's not simply a bug to begin with... since none of the other island quests are repeatable.
If you conserve your raptors and spam the ever living bejesus out of the up button you can complete the quest dozens of times pretty fast. The best setup is when you get raptors on the rhino or robot maps, that makes it go even quicker.
Probably best to get while the getting is good, before they take notice and nerf it. :(