I have never seen the Cimex in action but I have seen the Brute at WF last year, I remember noise. I have a GLS and I don't see how anything can be quieter than that. I will just have to wait until Mikefest to hear the Cimex.
I have Cimexs and a GLS. I used to have a 20 inch Brute. The Cimex and GLS are very quiet and smooth. The Brutes I had were junk. The first one I had the handle fell off while working with it and the pad driver wouldn't stay on. The thing vibrated like mad, especially if you had to pull it back. I exchanged it for a new one and it vibrated just as bad. Best thing I did was get rid of it even thought I lost a good bit of money.