I bought a WR450 last year (my first bike in 10 years) and when I first started riding it, it kicked my a$$. It got to the point where a couple months ago, I started looking into trading in on a new WR250 but decided to keep my 450 after all. I'm a little bigger than you - 6', 270lbs so I stiffened the rear suspension by 2 clicks and the front by 2 clicks. Other than putting a YZ throttle stop screw in (or just cutting the stock WR one to YZ length), this is the best mod I've ever done. When (or if) you get the WR450, I really suggest tweaking your suspension. It was a huge help to me. For tight trails, a WR450 is a pretty big handful. It's manageable, but after a few miles, I start to get worn out. A WR250 would be better in this situation I think, but the 450 works. But in more open trails, the 450 really shines. A 250 should be able to haul you around pretty good. My buddy's CRF250 has enough "go" to get me moving pretty good. But not quite as good as my WR450. Short term, you'd probably be happier with the WR250 since it's a lighter, more nimble bike. Long term, the WR450 will probably do better since you'll never run out of throttle.