I purchased the PF40 and had no issues with ecost. This was my only experience with them thus far though.
As far as the PF40 itself, I'm very happy with it. Although I was always skeptical of these things, I can say for sure that upon running my cable through it as well as all the component's power, my PQ is better than ever. I also had a ground loop issue with my cable and subwoofer amp, completely gone now. I'd highly recommend it.