Vaulta,
I just got back into riding after a 10 year break. I used to ride a CR-250. I talked to a few of my buddies for their input. I was gonna get an old XR or a TT, they told me I'd be totally disappointed if I chose them. They said, "After a week of putting around, when you get comfortable, you'll want something faster".
I got a good deal on an RM-250. Sure it was fast and took some getting used to. After a week my but wasn't sore from riding anymore. I mostly ride the woods on southern Maryland. When we hit the straights, I'm sure glad I have the 250. Nothing like ahifting gears on a straight-away wheelie.
I beleive in haveing the best bike you can. Even one that is above your current skill level. A bike that you can grow into, not one that you have to modify to keep up with you. Good judgement helps too.
A good suspension is very important. A 250 MX bike will come with a great suspension and good low end. If you want more low end power, a set of reeds designed for torque($35) will help. If your trais are real tight and the gearing seems high for your riding style. A smaller front sprocket ($15) will cure that.
I'm not knocking the KDX, just putting in a vote for the 250.
Hope this helps, Steve.
believe bigger is better.
desition