Great exposition. Reading your articles some seven years ago convinced me that $75 spent in acoustic treatment could equal or surpass $7500 spent elsewhere. This test seems to confirm that. Buyer beware.
I sell the Sorbothane feet which I believe are similar to the Iso..... product you tested.
I was testing in a different manner i.e. the noise being generated on the underside of my mixing desk by monitors sitting on the mixing desk.
My results also confirmed that foam pads provide absolutely no isolation whatsoever and in my tests and in some cases actually made the resulting sound under the desk worse than having nothing under the speakers - one of the many "Emperor's New Clothes" HiFi stories. In fact a stack of magazines provides infinitely better results than putting a piece of packing foam under your speakers. Lumps of Bluetack are better still but the best I found was the Sorbothane feet.