It depends on what you want. Is your goal to use the Pi? or is your goal to use xbmc?
If the goal is to use the Pi then I would push you incredibly towards helping with qOrbiter on the rPi. This will be an 'integrated' way forward for orbiter/md control/media playback on the pi. We need a DCE aware libCEC device to run on the moonPi (this could operate as a standalone DCE-libCEC interface on Pi and it could also be used on a moonPi). We need testing. I don't know if more than 2-3 people have even tried to install an MD on a Pi, and I only hear from 1 or 2 people sporadically.
If the goal is to use xbmc (on whatever) then an xbmc device and plugin could be pursued. I don't see this as useful unless complete orbiter functionality can be brought to xbmc. Use nfs/smb/upnp/dlna connectivity to play media from the core otherwise.
Both have their usefullness. For lmce project purposes I will push qOrbiter and moonPi.