Here is my evaluation:
My brother & I bought brand new bikes back in 2003, he got the CRF450 (the MX model, without electric start) and I got the WR450. We both motarded our bikes for the street, and rode dirt as well. His CRF was very fast from 0-70mph with the mx close ratio transmission, but he was always having valve train problems-hard starting, excessive use of oil, etc. His engine detinated in 2005, and has been in a "box" ever since. He could easily do roll-on power wheelies in 5th gear, but he always complained that he could not find the right gearing for street use.
I just sold my '03 WR450, and had accumulated over 10,000 trouble free miles with only (1) valve adjustment. I purchased a 2007 WR, and got a set of WARP9 SM 17" wheels, brake rotors, sprocket, carrier and everything for $850, tires for $200, and coverted it to street legal for another $75 in parts.
I really like the wide ratio transmission on the WR's, because you can get a nice highway cruising speed, yet still get easy take off's because of the low first gear.
KTM's are great bikes, but the best price I could find on a 450EXC or 530 was still $1,500 more than the WR. So I saved the $ for SM wheels, tires, etc.
Let me know if you have any further questions, hope this helped in your decision.