Anyone ever add Rick Fogel's dampers (from Whammadiddle)?

[Martin]

I realize that it would be much, much easier to add dampers while a HD is being built, but I do not have the money for another HD right now. I also realize that there are other ways to dampen your strings, but I'd rather attempt something aftermarket if possible.

Has anyone ever successfully (or unsuccessfully) installed the aftermarket dampers made by Rick Fogel of Whamdiddle?

Here's a link. You'll need to scroll all of the way to the bottom.
http://www.whamdiddle.com/instruments.html

Thanks.