Actually, let me clarify this statement, it isn't clear
"All works great - however, as per the subject, if we are watching a channel or a recording and the VuPlus starts or stops a recording the stream to XBMC crashes and I need to restart it."
XBMC stops playing the stream and just displays a single frame.... most of the time you can stop the channel and then start again and it will work straight away (though you have missed a few mins). Sometimes though XBMC crashes altogether and the Rpi needs to be power cycled (only happened once)
Thanks
Sz