I adjusted the preload on my rear Fox Qs3's by 1/2 inch right out of the box and the top 3 or 4 coils are compressed and touching with no load.
So to me, they are useless.
Still a better ride than the self adjusting shocks. The QA1 springs are looking pretty good right now.
The Fox progressive springs are great so long as you don't increase the preload too much. The upper part of the spring binds, yes, but it doesn't negatively impact spring performance. The gain is in lighter rebound rates for a smoother ride, and it helps reduce body roll in cornering, too.
To achieve desired ride height, you may want to increase the preload, depending on how much weight you normally ride with. Increasing the preload reduces the installed spring length. If you increase the preload to the point that the spring is less than about 12.8 inches, the whole spring can bind under a heavy hit. That is how shock mounts break. Jack up the rear and measure how long the spring is with shock uncompressed. Less than 13" is pushing is IMHO. I posted the details on this here:
New Fox shocks on, but . . . - The Honda Side by Side Club!
If you are normally carrying a couple hundred or more pounds in the rear you can consider another spring, which means a linear rate spring unless you can find a custom spring maker out there. I went with 325# Eibachs, but would probably go with 300 or 275# if I did it again. The Fox QS3's work great for me at their pricepoint for rocky terrain and the occasional fly down smoother forest roads.
