I have a Euro-Reef skimmer with two Sedra 5000 pumps, and it runs great. No regrets. Silent over all, though the sound of the actiivity within the skimmer resonates a tad.
I also have an ASM G-3, but haven't started it up yet officially. During its cleaning two weeks ago, it ran quietly but it was outdoors in a vat full of water & acid. The noise was water pouring everywhere rather than the skimmer making a racket. Once it is set up cooking live rock in a bin, I'll know if it is really quiet or not, but I have a feeling it really is going to be acceptable.