Tom, my setup is on oak flooring. I posted a fuzzy photo of the assembly at AA, the link is shown above. You might have to right-click on the photo holder and choose view image.
They were downright frustrating for me initially as I was trying to use them in conjunction with Machina Dynamica Promethean bases. I have since found out that anything that resonates is not compatible as part of the Promethean assembly. One could see their huge potential, but there were too many drawbacks.
Used simply under my loudspeakers they work quite well. I do not find them to be linear, but they sound so good I am willing to accept some drawbacks. They are perhaps too smooth, but inserting the small DH Cones returned some of the "snap".
These unusual footers were brought to my attention by Ric Cummins at Rosinante. They have proven to be fascinating, engigmatic, frustrating, and above all else, most effective.