You are right in that I have not experienced ARC. But to say nothing will sound better without ARC is an awful bold statement to make. I am not trying to be argumentive or slam Anthem in any way but for me it is about choices. With the MRX lineup I would have no choice to see if I would prefer using ARC or straight analog. The other factor is that the MRX 500/700 are not inexpensive AVRs and at the cost I would want certain features.
For me when I sat down to listen to music today with my Parasound 2100, BDP-83SE, BA A7200 and Salk SongTowers I was extremely happy with the SQ and simplicity of my system. It just really surprises me that Anthem did not offer an option of an analog bypass for the analog inputs. At least offer a 7.1 analog input on the MRX 700 but Anthem decided not to.