I love mine.All I have done to mine is put the necessary guards for off road and a 12 oz flywheel weight and it is good to go.I did just get a 18" rear wheel only one ride so far.
I tried a YZ250 and didn't like it at all. It might have been the gearing, but i just wasn't comfortable at all. hoping to find a nice EC but found a really nice MC and thought it might be okay.
RPDuc, who used to post here quite a bit (and who is a good friend) rides the MC250 with us. He flies on that thing. He has a 2005 with the six speed. Does the 2003 have the four speed? The four speed might be the only down side. Otherwise, why not?
Mine has the six and yes it fly's.It is also quicker than most I like to mess with my buds by passing them coming out of corners.It lifts the front easy with no clutch.
It came on the power valve quick but after just a little while you can tell when it is about to open.The F/W weight was just what it needed gos just as fast just a tad longer to rev up.The funny thing is it is just as happy lugging around or revving the piss out of it.