WOW, cool bike. Ride Report ASAP, ok?
 
  
Stay up a gear and hang on! 

Power delivery is manageable because unlike the CR500 it is a power valved motor. The power valve also extends the power band about 800 rpm. I have two riding partners that own two stroke big bores. One had a CR500 (sold it after to many near death experiences) and the other that owns two KX500's of different years. After some comparison riding for power delivery I chose the KX. From what I've researched the KX500 only makes a couple of horse more than the CR500 but IMO the KX500 does a better job of getting the power to the ground because of the KIPS (power valve). That being said both machines are about equal so pick your color. 

The bike will come up in any gear on the street with just throttle. In the desert in fourth and fifth I'll get surprised once in awhile but mostly it's just digging a big trench! Bike pushes a little in the corners sometimes but overall has the best stock suspension of all my other bikes and will cruise the roughest desert like an old Caddilac with only two brakes. Two of my other partners have 450F's and this machine will just walk away from them when I decide to twist the throttle! 
 
 All of my riding is off-road and desert so I can't provide any input as to what it does on a track. The only negative for me is that I'm only 5' 10" and the Kawsaski is almost two inches taller than my next tallest bike.
I also own an "05" RMZ450 and a "11 KTM450SX-F so I feel I'm qualified to speak on which bike is faster and give an honest report. I'm presently planning to work my way back to all two strokes but maybe keeping the KTM. I just spent $2000.00 on the RMZ for a complete new top end rebuild using the original bare head which also included porting and a new cylinder. That's not happening again! 

I'll post some fresh vids of the KX500AF next time I roll it out! Oh, I forgot to mention I also own an "07" RM250...fun machine!