Shunyata Denali vs PS Audio P3

Has anyone ever compared these power line conditioners? I want to buy one or the other but I have never used either. After reading about them, I suspect the Shunyata is a better solution but is it significantly better? I suspect the biggest difference would be experienced when using mono block amps, which I do own, so I am curious. There is quite a price gap between them and I doubt there would be an audible difference, but I hope I am wrong.
As was mentioned in another thread here on Audiogon
you might see if you can demo both of them from The Cable Company if no one gives you some direct comparesons.