I think that it will depend on how the implementation of manual focus is going to work. I've tried manual focus on the screen with the 50mm unit. A smallish patch enlarges in three stages if desired. This works quite well for macro but I'm not sure if it would be good enough for a real manual focus lens. I haven't got the evf so perhaps it would would work much better with this, I just don't know. I think the focus for manual lenses on the NEX is better because the whole screen enlarges.
I think this is a module specifically for MF rangefinder lenses, and it is Ricoh we're talking about, there is a chance for much better MF operation than existing mirrorless cameras with adapted legacy lenses.
In addition, all the other mirrorless cameras have problems with wide angle RF lenses (corner smearing). I would think Ricoh will design the sensor system for this, since it is a dedicated M mount module.
A friend of mine works for Ricoh, though not in the camera arena. I think he has a GXR. It might be worth seeing if someone will have a Leica module after it's released so I can play with it. So I'll wait and see.
That said, the modular system is kind of both genius and retarded at the same time: there definitely are advantages to sealing the unit (dust and all that), but it does make certain repairs more costly. I hope the sensor's worth that kind of commitment, though I remain doubtful. Also, it seems like the modules would be a PITA to store as square/rectangle shapes don't pack as closely as smaller round shapes.
My first thought, though: I'd rather use Leica lenses with a rangefinder -- any rangefinder -- 99% of the time.
Ahh, but instead of just storing a lens, what an interchngeable lens mount module means is your storing a completely different lens system -for now manual Leica RF or very likely other mounts such as M43 or Sony E - with AF and zooms and macro facilities that never existed on a manual RF lens. You can have it all it each format's native capability - no other camera design can do that.