A well set up and well ridden KDX will show it's rear fender to many faster and more powerful bikes when the trail gets ugly and tight. Easy-to-use power and friendly, predictable handling will increase the average rider's speed far more than tons of power that is usually wasted in wheelspin and steering corrections.
I have been riding for a couple of years and bought a 00 KDX 200 last year and have been really impressed with it. From what I have heard, the bike is very reliable and easy to modify/upgrade. The bike has loads of power for woods riding. I'm 5' 10" and weigh about 155 lbs. My only complaint is that the seat height is a little tall for me. But other than that, the bike performs flawlessly.
I used to own an '89 KDX and now i own a '94 KDX 200. I just love them. Very easy and cheap to own as they do not chew though tires and chains and sprockets.
People are always bagging them saying that they are slow and are a trail bike, then they go out and buy a bike with more power than they can possibly handle!!!
I would like a KTM200 but until someone hands me an extra $4000 ill stick with the KDX.