Here is the thing about ANY powerplant, not just the P10. It helps where it can and when it can, but that is all. Lets consider my example. I have a PS Audio P5. It is enough for my equipment. On average it launders 50%-55% of power, the THD in never exceeding 2.5% and THD out (the clean power) never exceeding 0.1%. So, do I need it? Judging by the THD and the scope graph that shows me how much of a clean up is happening, it tells me that if I disconnect it and somehow do a double blind comparison between wall outlet and the P5 I will not be able to tell the difference. Why won't I sell it then? It looks cool, that is all. I even think of getting the P10, but then paying double for doing exactly double of nothing which equals to guess how much? Right, nothing.
But if your power is exceptionally dirty, it fluctuates by 5V-10V and you have a tube amp, or there are a hundred current hungry devices on your local power line that introduce devastating noises (vacuum machines, drills, hair driers, etc) or your THD in is in the 30% or even higher then you definitely need some power plant or another. How many people actually fall into that category? I'd say 95 out 100 PS Audio power products purchasers dont need them in the least. Me included.