Audioquest Niagara 700 vs. PS Audio PowerPlant 20

I have the Niagara 7000 and really can't say anything bad about it, but I'm intrigued by the PS Audio P20.
What I like about it in theory is that it makes clean power from what it's given from the grid, where the Niagara simply filters the power.  Michael Fremer wrote about his issues with the power feeding his home in a recent Stereophile, which is what got me thinking about this topic.
I'd be very interested to hear from anyone here who has compared these two components and would like to share their findings.  
Thank you in advance!
Peter