I am planning to buy an off-road bike for aggressive trail riding. I would consider myself an intermediate-level rider. The territory I ride in is rocky and speeds vary from 1st gear rock beds to fire roads. I want a bike that can take what I can dish out. Should I buy a KDX220R or a WR250/450 (I would lean toward the 450 if I buy the Yamaha)? Also, I can get a great deal on a 2003 KX250 but I think that it might be a bit much for the slow sections. Thoughts?