I'll admit, at first glance it looked like garbage...but after hearing some of your claims I'm interested. It could very well improve groups significantly--I just didn't think it was massive enough to affect resonance. After thinking about it, though, I think it has a lot more potential than what I first credited.
For $20, any improvement would be great--especially considering people easily spend 10 times that working on other parts of the gun for the same results...