The regenerators still create some distortion on the line. A 'percentage'.. So they may want to give the illusion they make perfect AC but in fact they are really about as good as other good power conditioners.
The downside is it takes power to regenerate. the old ones were using twice the power that it put out as usable AC. The new ones are better, but they still use up a third more power.. So for any large power-hungry device like an amplifier they are just not efficient enough to please any 'greenie'.
I owned a PS Audio PPP and sold it. Anytime the plasma TV was on the PPP fan would start whirring away.
I bought a used Furman REF20I. The Furman is way better!
Later I bought a used PS Audio P600 but ONLY because I wanted to play with a feature it had (with an optional board) of being able to produce alternate AC 'frequency' So instead of a 60Hz sinewave, it can make a nyHz from 60 to 120 (Someone in Stereophile mentioned playing with this to some good effect, and I wanted to try it.) So I use my PS Audio P600 regenerator only for a few digital items. It wastes power, but so what, it is only a few dozen watts.
So what I am saying is folks are not realizing the regenerators are NOT making a perfect sine wave. Just a somewhat better one. AND, as I wrote,the other types can certainly do as well. Without wasting a ton of electricity doing so.
I would not trade my Furman REF20i for any other conditioner.. It is all I can want in one. I would say I find the powerfactor conditioners to be great. Other Furman I have no experience with.