We have one of each, though the CS is currently in Kenai's quarantine cage, but I can say that both do make some noise, but not a lot. That may also have something to do with the weight issue - Koko has the FS in the Ferret Nation but he's only ~450g, so he'd have to try pretty hard to make such a racket. Kenai's quarantine cage (with much flimsier bars) is in the bedroom though, and the noise from his CS has never been enough to keep me awake (light sleeper here). So I suppose I'd have to go with the CS.