Newly released spy footage shows a Groundhugger XR2 in it's natural environment.
Thanks to David Wolfe for the video and for the construction tips. That's him piloting his own XR2 in the video. His construction diary is here.
In other news, with the assistance of Mrs G, I removed the internals of my Nexus 8 hub, gave them a spit and a polish and put them back together. The dropouts on my mountain bike were long enough for me to be able to get the hub in and tested, albeit without a functioning back brake. The hub appears to work fine, gear selection is painless, and there's no drag from the back end. I'm now confident in using this in my final bike.
I'm keeping an eye on Ebay for some of the other components I'll require. I'm also planning a trip to my local bike recycler to have a rummage through their parts bin