I suspect my first task is going to have to be a test harness. The refrast runs at extremely low framerates - several seconds per frame, though in some cases it seems like we might be talking minutes - so the best way to test programs will be by recording the output as a video and then playing it back afterwards, as the guys at MS have been doing.
It also means that all of my demos will need to be non-interactive - cameras will have to move on predefined tracks and so on. That's not too big a deal. It might make things a bit easier - I can make all the simulations stateless, allowing me to render a frame for a completely arbitrary time.
I'll probably go for something that loads a given demo as a DLL, and provides the D3D10 device in a separate thread - that way I should have no trouble keeping the UI responsive while D3D is working.
When the harness is done I could probably release it to the public, if people are interested.