Preach!
It's a well-engineered product, but grotesquely over-priced. A good alternative would be Whispermat, but it only has the decoupled barrier and the OCF, so you'd need a layer of deadener down first. Again, with the OCF, you're looking at moisture issues, so you'd want to film-face it with foil or mylar and hit it with some sealant.
and you may not even need a full layer of deadener. I just ran a series of tests using a very crude version of the standardized tests we have been screaming for and it actually seems to be working. It looks like my previous attempts to devise a home brew vibration damping test procedure where over-thought.
I started with painted 12"X12" aluminum sheet metal blanks and drilled a hole in the corner of each so they could be suspended by string - like a percussionist's triangle. I hung one up, hit it in the center with a drum stick and rang like a cheap cymbal and had a nice long sustain. I then covered the corner farthest from the hole with a 6"X6" square of Dynamat Xtreme. To my surprise, it was dead as hell - just a ping with no audible sustain. I repeated this with new blanks and Cascade V-Max, SS Damplifier and Damplifier Pro and all responded similarly. I'm pretty sure that if I had started with smaller pieces I might have found differences between these products, but excellent deadeneing with 25% coverage represents a threshold I found interesting.
Then I moved on to Peel & Seal, curious about the performance of asphalt vs. butyl. This should be the same result you'd get with FatMat. 6" square applied like the others and while there was an audible drop in the resonant frequency, the decay time was not noticeably shortened. I kept adding more until after adding the equivalent of 4 6" squares, the resonant frequency had dropped significantly (but still audible) and the decay was shorter, but still present. 4 times as much Peel & Seal didn't perform as well as the products that met the threshold test.
I moved on to eDead v1SE² - butyl adhesive with a Mylar facing instead of aluminum foil. It took 3 6" squares to get something close to 4 of the Peel & Seal. Again, not as good as the first batch of products - 3 times as much material and inferior results.
I'm waiting for some liquid deadener to fully cure, but it looks like it's performance is going to be somewhere between the extremes I saw above. People are obviously going to attack this procedure and I welcome them to try to find something better, but it seems absolutely clear to me that butyl adhesive and heavy aluminum foil are a winning combination and that the point of diminishing returns occurs much earlier than I expected.
