Thanks for your insight.
As you note, neither the Sonos or the Yamaha MusicCast speakers are high quality speakers and they would probably not show the quality of DSD and high rez audio versus CD quality. I actually convert all my high rez and DSD to CD quality for use with my Sonos system.
The WXC-50 may be an better unit than the Sonos Port, at a cheaper price. But either is a specialized use, not a common part of the typical wireless system.
I would not, and do not, use Sonos for a high quality, audiophile system. But, Sonos is a good option for a casual, whole house audio system. For that, I do not see any advantage to the Yamaha system. I have read more than one account of wireless problems with MusicCast, whereas I do not see many accounts of those problems with Sonos.
Thanks for your thoughts.
By the way, if Sonos provided a full DLNA system, then all of these problems would go away. It is unfortunate that they decided not to do that. But I do understand that they do not want to give up their UI as a part of their system.