SO had a good play with XBMC in the weekend and put it on my main PVR box.
Have left it on there, but after spending a big of time with HIP I couldn't get the remote working properly. Especially the directional keys.
Seems HIP/URB-UIRT with a Harmony pretending to be an MCE remote wants to send a numpad6 to XBMC for the right key, rather than the right arrow key.
I guess my two solutions are spend a bunch of time trying to get HIP working properly (and considering it's probably not developed any more), or get XBMC to accept the numberpad6 - which I think it more likely to happen.
I had a toodle with the keymaps.xml but don't really know what I should be putting in there.