I have a Carlyle in my master bath and have not had any issues with it. The unifit adapter allows a little more noise than an all porcelain trap, but I do not find it annoying at all - Totos tend to be fairly quiet, so it is a relative thing.
We decided to keep the toilet and either build a small shelf wall behind it or build the wall out another 3 inches (the entire wall). I think I understand all of this now. Thank you.