I got a SONOS system a few months ago (thanks to a small inheritance from my aunt). I have a Connect hooked up to my home theater system, two Play 5's (one in the kitchen, one in the living room), and two Play 3's (one in the bedroom and one in the office). I have to honestly say that these are the greatest music/media related purchase I have ever made. I've tried so many ways over the years to easily get music networked in the house and this is the first time it's worked flawlessly. (BTW, I put the blame primarily on the hardware, not MC....) In the several months I have had the system going (in two separate houses now), there have been maybe 3 or 4 glitches in playback. It's rock solid!
I was saddened, however, that I would not have access to my awesome (and painstakingly curated) MC Smartlists. I started by going to some of my smartlists and exporting a whole bunch of them as pre-programmed playlists that SONOS could access. While that was okay, it would require going back every so often to create some new playlists.
After reading this thread, I went and checked out AllShare, and sure enough it could see my MC library as well as my SONOS players. I could now push my playlists to the SONOS system. But I find the AllShare pretty clunky and these days with the SONOS I do most of my music selection through mobile devices (iPad, iPod and Android).
This lead me to the Twonky app which does a much better job of sending my MC smartlists to my SONOS players, making me VERY happy!
I mention all of this in the hope that my friends at JRiver see that this can be done and perhaps find a way at some point to get MC to recognize/play-to SONOS devices via zones or whatnot....