I am using Sonos (actually on Version 8.4) and subsonic, too.
I have no issues at all, except some latency due to my large library, especially on starred albums.
but please check
http://www.subsonic.org/pages/sonos.jsp.
If you configured subsonic using the page it is my understanding that the protocol has changed and been extended slightly. Maybe a reregistering works for you.
Another solution to try is to reboot all Sonos devices and then the subsonic server. Upgrades sometimes confuse the interconnectivity between the two.