I ran one for two years, then broke down my tank, moved, and set up another with a DSB in the sump -- again for only about 3 years. Most of the "break-down" problems I've heard of come after 3 years, so I can't really speak to that point, but I believe I had a lot more small life in my tank then than I do now with about 1/2" of crushed coral.
And I won't add anything to that because it isn't personal experience -- I would just be summarizing what I read on RC and from Dr. Ron a few years ago.