I haven't, both the full squish bikes I owned had coil shocks. My current MTB is a fully rigid 29er. When mountain biking was the main focus of my riding, I used to be willing to spend the time and money on all the goodies. Now, I've become pretty competitive with road and cyclocross, and I only use my mountain bike for cathartic recovery trail rides through the woods with my dog. Maybe if I get more into trail riding again, I'll try the latest and greatest suspension systems, but for now, I'm all about low maintenance.