I'm not sure whether or not applying the new system to old input is a good idea; I'm leaning toward agreeing that it wouldn't hurt very much. But I don't think there's any need to go back and make those changes to all of the thousands of levels on J2O, and I also think that some authors of both levels and reviews might be concerned that their pages are being altered. My recommendation is to allow level authors to request that reviews of their levels be categorized, but leave the rest of them alone.