I use the Stillpoint Ultra Stainless Steel (SS) under my speakers--Sonics Amerigos. They have been a huge improvement across all the usual dimensions--sound stage, bass, overall tone, etc. My listening room is carpeted and that has always posed a problem. But with the Stillpoints it has totally negated it that issue. It was a great investment.
However, for the rest of my system I decided to try Spiral Groove's Strange Attractors. These are (somewhat) more cost effective and I so I started out with using a set under my phono stage (Herron VSTPH-2). Again, another great bump up in my systems' performance.
Since then I've added the Strange Attractors to the rest of my system--under my line stage, amp and Finite Elemente rack. Again, each time I noticed a very nice improvement, especially when I put them under the rack. (I'm not using them under my table--Spiral Groove SG-1--as that has its own custom feet.)
Now, I feel like I'm really hearing my system at its best. It's really pretty incredible. (And I thought I was happy before going down this path.)
So, I am definitely a believer in "vibration control" or whatever you want to call it. Obviously, I haven't tried everything but I give two huge thumbs up to both the Stillpoints and the Strange Attractors.