>>Exactly what I've been waiting for. <<
Same here.
The Hexar Af was it in film. Quick focus, great to handle and a terrific viewfinder.
As for viewfinders, I also have the M4. The viewfinders in the M4 and the Hexar AF make the X100s viewfinder look like a toy.
But, despite the distortion of the framelines in OVF (the framelines bend inwards), the X100s works. The shooting data is there before your eye. And in EVF mode there is none of that pincushion distortion. Although you do have to get used to the LCD rendition of the scene, which is not so jarring after a while.
One thing that is a little like the Hexar AF is that the focus rectangle in the X100s OVF can be set up to move about while compensating for parallax as you get in closer. I won't try to explain it here; you will be able to set it in the X100s menus. It's very useful. With OVF. Not needed with the EVF or LCD back screen.
Low light performance is wonderfully good. With matrix metering (showing my Nikon upbringing!) it gets things so right in varied low-light scenes. I think more satisfyingly so than the D600.
And I have had quite a bit of fun with it setting the Aperture to A (auto) and the shutter dial to A (auto) and letting Auto ISO have its head. It makes choices that are uncanny. I have the ISO auto set at Base 200, upper limit 3200 and minimum shutter speed 1/125th. With that set-up it took a shot of a wooden statue in a church at 3200 ISO and at 100% I have difficulty picking the difference from 800 ISO.
But I miss the subject isolation of the 50/1.4 on the D600, and the breathtaking rendition of a Summitar/Summicron or 90/2.8 tele-Elmarit.
However none of them are as compact and/or swift as the X100s. And it's files are superb.
Dave, I am using mainly Jpeg. Tried a few RAF files in Silkypix which I've never used before, and it was really hard work. I have been using Aperture 3 and may have to get LR 4.4 or whatever. The Jpegs look really good (bear in mind I've only had this thing for about 48hrs) but I am surprised at how small are the Jpeg files - about 3mb (although I could be mistaken - that's Jpeg Fine and Large - the Owner's manual says that Jpeg setting should print to 11x14 or so). The RAF files were reading at about 30mb in Silkypix.
I'm taking it with me on the Camino Frances (to Santiago de Compestella from St Jean Pied de Port) next month.