I have both:'00 KDX220 & '05 300exc.
I was going to keep the 220 for a spare bike because it has a few mods and is a real nice bike. But I think I'll have to sell it...
The KTM fits me better(6'0,170lb.),it's a longer bike,has better high speed stability,slimmer,way more power,comes with most of the good stuff already on it.
My KDX always feels a little squirrely at speed on dirt roads but the KTM is straight and steady.I like the KDX alot,and if I only rode in the real slow tight stuff with no big hills,it would be fine but for where/how I ride the KTM is the winner.I like it way better than my WR450(sold) too.
p.s. Kawasaki would be smart to come out with an updated KDX .