I have theem on my 450r right now and they are probably the best tires I've ever used. They've been holding up good so far but they're real soft so I don't know how long they'll last. I have pics with them on the rear under readers rides.
The MX-R's are meant to be super soft, so wear isn't their best trait. But they are designed for MAX traction, and for those really hard pack tracks that turn to clay after the first motos. They are super light too, less unsprung weight, which is always good.