What I want is fairly simple, but apparently not yet achievable.
Body: about the size and shape of a Leica M with a bright 100% viewfinder.
Lens mount: Leica M (Voightlander make affordable lenses for this mount)
Sensor/DIP: equivalent of D700 sensor and image processing would do fine.
Other features: simple interface, good autofocus, auto-exposure, stabilisation.
Price: under a grand, maybe up to £1500.
I'd happily settle for something the size and shape of an F3 with Nikon F mount though, which ought to be a bit easier to produce using current technology.