Hello guys:
If you own a 400EX, you've got a linkage system that is VERY similar to the CR 500.
I never did it on the 250R for a couple reasons.
I wanted the 250R frame, (and the new EX & CRF frame) to be at a reasonable price. The CR500 linkage is a couple hundred bucks on it's own, and then you need a very expensive shock to go with it. To me it defeated the purpose of a cost effective frame project. You will also need a special swingarm to make it work, and that also adds cost to the project.
As for the ride, I have tried them, but to tell you the truth, I'm not a good enough rider to push it like it needs to be. On top of that, most of the guys that own one have a very good ride also because they own the best shocks available.