I love my XBMC and have had great success sharing a single datasource and database across multiple clients.
With one exception – my linux box doesn’t like it when you pause TV and movies when the video file is on a remote SMB share – whenever you try the videos stop playing. Manageable, but it annoys my wife.
I think I finally fixed it. I created a symbolic link on both the Windows and Linux clients so that XMBC thinks that the file is a local path. This is necessary because all of the clients need identical paths to the video files in order to share the common database.
So far so good, I can fast forward, rewind, pause and the videos seem to handle it fine.
Update: Nope, never really fixed it. I ended up switching to Drobo and sharing content with both NFS and CIFS. Ever since I made the changed everything has worked like a charm.