So I binned the RPi since it wasn't manly enough to do the 1080p/5.1 stuff I needed it to, which it mainly down to the lack of gigabit ethernet than the unit. I've been using my old work laptop running Win7 for the past few months, which although has run XBMC perfectly, it doesn't handle closing the lid but staying on very well. It was always a temporary method, though.
I wanted to get a proper EeePc to run XBMC on, but never quite found the £400 or so to get the one I wanted. In the meantime, like yesterday, I discovered that Plex have released a client for the Xbone, which sounded intriguing so I looked into that a bit more. Long story short I installed the server side client onto my UnRaided NAS last night, and tried it on the desktop PC via browser. Whilst it wasn't initially as simple to use as XBMC, I got my head round it quickly and it worked a treat.
The next step is to get a Plex Pass for $4.99 a month (or $40 a year, or $150 lifetime) and see how the Xbone app works. If it does what I hope it will, then I'll get full access to my media with no extra box, and it'll all be voice and gesture controlled
MS are bringing out their own app for this soon, but I'm doubtful it'll work that well with UnRaid. Time will tell, and for $5 I think it's worth a punt. Using Plex also means I can run the app on iOS or anything really.