I would highly recommend the purchase. I just bought an '02 250 EXC coming from a 2000 KDX. What a difference. Much more power all across the board, outstanding handling, good brakes, roomy riding compartment, excellent suspension.
BTW I had all the usual goodies on the KDX such as FMF pipe and S/A, Race-Tech Gold Valves, heavier springs, etc. Still no comparison with the KTM.
I have not had the KTM past half-throttle since its still breaking in but WOW!! Talk about power.
I ride in Western Washington so the trails are fairly tight, although I haven't had the bike in really tight stuff yet. But so far no regrets. The bike is everything I had hoped for.
Good luck.