The problem for me with the FPS, is , that they say it's an "open " system, but it isn't at all, let me elaborate .
Take the now discontinued Sinar M,
For me that was the first real step towards a 100% modular camera (pitty they didn't make it open for all backs but hey, it was a step).
It lacked a few options, like changing from brand of lens easy without having to carrie multiple prim element,s, and so on..
But the concept was: 1 DB, an electronic shutter, you could choose a prism viewer , and what lenses you wanted to use and so on.. You could choose to only use the electronic shutter on your view camera, or to use it without prism, but you could also choose to make a DSLR from it, and if you wanted to use Sinar lenses = fine but if you wanted to use nikon lenses := also fine..
That was the first step to a real dynamic "open" system, you can do what you want with it..
A combination of, the Sinar M & FPS & Hcam, open to All brands of Tech-Cams and lenses and backs, that would be a body / system i would be happy to invest 10's of thousands in.. like film back or shutters in the good old days..