The PV KX500 motor is awesome, but the frame/suspension/plastics are really, really, really dated. I've ridden both and owned a CR500 for several years. You really need to decide what type of riding you're going to do with the KX. It's rake/trail numbers are more relaxed and therefore lend themselves to highspeed, WOT situations (sand dunes, desert racing, hill climbs, road supermoto etc.). The stock carb is a great unit but can be difficult to tune (if you're a carb novice), especially when you start playing with the PV timing. These two things alone are why most opt for the CR; It's more user (read:idiot) friendly and really a turn-key, all-arounder type of bike. The KX also doesn't have nearly the aftermarket available to it nor are there as many AF kits/conversion companies. Also be very careful reading your plugs/piston wash as rebuilds are very expensive and IIRC the KX can only go 1 over.