I was the one with the question about the white scales turning silvery in some areas. The basic responses I got were yes we see them, and no they don't seem to be an issue. This was my same conclusion, so I am not going to sweat it, since mine eat like pigs, have put on a huge amount of weight (all three came in with their spines visible) and have grown noticeably.
I agree they have gotten disproportionally more pricey recently. Once established they are beautiful and easy additions, that don't bother other fish, all pluses in my book. I wouldn't even consider buying any without a proper/complete quarantine regiment.
Just a side note, I think the terminology gets confusing by saying there are black zosters and yellow zoster, especially considering the variation of the head on the), when really only the black and white version is actually P. zoster. Also IME the head color on the pyramids changes with "mood", time of day, etc. Really settled "happy" pyramids all have dark brown heads. BradleyJSyphus has some for several years, check them out!
