Seems to me that focus is the main issue of all of the mirror-less cameras. It will be interesting to see how the X100 compares to the Ricoh GXR/A12 50mm and 28mm camera units in this respect. Ricoh has improved the AF speed greatly though firmware upgrades, but the AF is still not fast enough for "street" (or "gallery") photography. On the other hand, using the superfast AF of topline DSLRs for street photography is also problematic because the camera ends up often focusing on the wrong subject when shooting closeup, say, 1-2m, in a dynamic situation. That is why the MF pre-focusing of the Leica-M cameras is so effective as a basis for zone-focusing.
On the GXR the manual focus using the enlarged rectangle on the LCD is virtually useless, as pointed in the Sean Reid's review, because it's so difficult to judge what is in focus. What I do with the GXR is to use AF to pre-focus on what I want to be the plane of focus and then, using on the function-assignable buttons, switch the camera form AF to MF, which locks the focus on that plane. I wonder whether this method can be used with the X100.
Keith, it seems to me that this is a gift horse into whose mouth you will look.
—Mitch/Pak Nam Pran
Paris au rythme de Basquiat