Tried and failed - just freezes and dies trying to play 720p and above from the networked usb drive over wifi. Going to have to give up on it and just put it on a usb stick straight to the box.
I have a BT smart hub and have plugged a USB 3 portable hard drive to it.
I have advanced settings set as:
buffermode 0
memorysize 278921216
readfactor 20
This works perfectly with internet streams but doesn't buffer the shared usb drive at all. Unfortunately, I have no way of changing to NFS shares and the cifs share doesn't return anything.