Hi, Ric! Welcome to the madness of this thread.
We don't know precisely how manual focus will work on the X100 yet, but we do know a few things:
- the hybrid viewfinder will use "peaking", which highlights the in-focus edges with a solid colour (reminds me of Photoshop's gamut warning) so you know precisely what is in focus
- the hybrid viewfinder can potentially act as a rangefinder. We don't know that it will at roll-out, but we do know that all it will take is software. The camera knows where the lens is, it knows where the viewfinder is, and it could definitely provide a virtual rangefinder "patch" superimposed over the optical viewfinder image
Everything is conjecture at this point, of course, but there you go. This seems like a camera designed with manual focus specifically in mind, and I would be very surprised if the software did not include some sort of rangefinder-like behaviour. As long as the focus ring is mechanical and not fly-by-wire, a virtual rangefinder could indeed be
good enough.