Read this review a couple of days ago and didn't consider it a selling point for extremely heavy class A amps that take an hour to warm up. The comments about the relatively poor bass response (by comparison to other very expensive monos) struck me as a killer. Your points about distortion by-products second this conclusion.
So Pass attracts audiophiles by its expensive entry level amps then tries to push them into the stratosphere with these more powerful engines. Guess it works...