I just bought a new '03 RM 250 a few months ago. It seems to be a great bike but I am only an average rider and am not riding the bike to anywhere near its capabilities. But I can tell you this, it's frigging fast through the entire RPM range. I'm about a 180LBS and the front end has no trouble coming up in 4th gear. It came in 2nd in most of the '03 250 shootouts, but only lost by a C hair to the YZ250 because the RM power was a little less user friendly then the YZ. The only major complaint for the bike was that it was difficult to jet properly. Apparently this was fixed for '04, and the bike won the shootout in one of the Dirt mags I read.
Good luck.