My KDX220 is about as fun and reliable as they come. I did quite a bit like KX front end and a Rev-Loc and some other mods.
I have a 250 KTM XCF-W also and it is hard to decide which one to ride. The KTM will be the better choice at faster speeds and rougher terrain. The KDX is just plain fun in the woods.
I stuck mine for sale in the flea market and put a "I don't want to sell it" price on it. Most likely take the listing down :)
2011 Gas Gas TXT250
1966 Honda 305 Scrambler