I've been shooting with the Ricoh GXR-28 for my fixed lens 28 and its gotta have the slowest AF of any camera of any size I can ever remember. Doesn't bother me a bit at this focal length. When I'm shooting a landscape or any other static shot, its more than fast enough. And when I'm shooting something I have to nail right NOW, I'm using zone focus. I fully expect to use the Nikon the same way. Even in fairly low indoor light, I've got zone focussed shots at f4.5 at well over 1/250 of a second at ISO 3200. From the preliminary images, it would appear (and one would expect) that the Nikon sensor will be better at 3200 and is very useable at 6400 and somewhat useable beyond that, where the Ricoh tops out at 3200. I can see wanting faster AF on the X100s - the 35mm focal length is where DOF starts getting limited enough that I'm only comfortable zone focussing in good light, so in low light I like reasonably fast and reliable AF for shooting anything alive. But the X100, after firmware improvements, was always good enough for me. So I'm sure the X100s will be that much better.
But I guess I'm also odd in that I don't find these cameras all that comparable. Yeah, they're both fixed lens APS based cameras, but one is a full featured 35mm focal length camera with two, count 'em TWO, built in viewfinders, and every manual control known to man, and the other is a very tiny and discrete 28mm with seemingly good controls and IQ that, for me, would serve a totally different purpose. I could see owning both and using them together as a walk around kit, like I often did with my X100 and GXR-28. Or I may do next with the RX1 and this or maybe still the GXR-28. But if I was primarily interested in what the X100s had to offer, I don't think I'd be giving this a second look. And if I was primarily interested in what the Nikon A had to offer, I don't think I'd be giving the X100s a second look. But everyone wants to compare them. When I get the X100s, I'll compare it against the RX1. When I get this, I'll compare it against the Ricoh GXR-28. But not each other...
-Ray