Nordost Sort Fut supporting audio rack: does it work?

I see that the Nordost Sort Fut appears to be used by some as expensive isolation devices for speakers. I am set in that regard, having bought Ingress Engineering speaker footers. If you are reading this post and are using Sort Fut to support your audio rack, can you comment on the wisdom of this approach? If your rack is supported by Sort Fut or a similar product, do you also isolate individual components on your rack? Which brand of rack have you attached Sort Fut to, and how is this an improvement over the stock spiked feet, for instance? Thanks for sharing your experience with this application. 
I haven't used them so take this comment with a grain of salt.   As an engineer I don't follow their logic on their webpage.   They might work just fine but I don't see it.   If you buy them, make sure you can return them if you are not satisfied.   Try to determine if the sound improvement is worth the money, otherwise keep looking.  Or spend the money on other stuff....
Thank you for sharing your informed opinion of this product, which is awfully expensive. I found a set at 40% off, but that’s still pricey compared to other similar products. My thought was that if I could add resonance control to the base of the rack, it might not be necessary to spend lots on resonance control for each component. I am currently using Agora Acoustics Magic Hexas (?) under an integrated amp and disc player, an inexpensive option that has pleased me. The Ingress Engineering speaker footers made a bigger difference...and are more costly. I’m open to any suggestions about resonance control under the rack versus under components, or whether both are better than either. 
If someone was to place four silent vibrators randomly at various places on your audio rack without your knowledge do you think you would be able to perceive their presence and hear any difference while listening to music? I doubt it. I have been to a demo where the CD and DAC were picked up and carried across the room while playing and there was no discernable difference in sound or quality.  You may want to give it a try before spending big bucks on something that claims to do something that has never been proven. Only claims and testimonials that are as easily refuted by listeners who have the opposite experience.  There are a lot of ads for gently used /like new tweaks available on various audio sites. Tread carefully 🤔 and Good Luck!