I couldn't read this full thread, it's too long-- I wish it had been edited into two parts, one before the camera came out, and the other after.
But, whatever. Last weekend I went with some friends to a drag strip that ran from late afternoon until well after dark, and I was shooting with a D800 and a 35-70 F2.8 zoom. By the time I finished, my arm felt dead. In addition to my Nikon system, I have a full Panasonic system including their version of the f2.8 zoom, and I wish I'd taken that one instead...I didn't, because I wanted more high-res tall verticals (it was a drag strip) from the D800's longer aspect ratio.
Unlike most people here, I am not obsessing over the Z7's lack of a second card slot or the sensor (more about those things in a minute.) I'm obsessing over its size. I looked at the camera size comparison website and guess what? It's about the size of my m4/3 GX8 Panny. It's slightly narrower and only a bit taller (because of the viewer) than a Leica M10, and weighs less. For me, that's huge. And it's weather-sealed. Also huge. It'll use my whole range of fairly modern F-mount lenses. Huge. The mid-range zoom is f4 and reasonably compact: terrific. I shot most of the drag strip at 1600 and the quality was excellent; I don't need no stinking' f1.4. Would I buy the f0.95 manual focus? Maybe. Although I have a couple for the Panny, and those work fine. Depends on price.
Second card slot and sensor: I don't care about the sensor as long as it works. I suspect it'll be about the same as the higher-end Sonys and Canons, and all, IMHO, are brilliant. The only reason I can think of for more resolution is that you're shooting for billboards, or the kind of larger-than-life model photos in Victoria Secret windows. Second card slot? Most interesting review I've seen for that came from a wildlife photographer who says he doesn't use a second slot because it's too slow, and that XQD cards have *never* failed him. They are essentially as good or better than the SSDs that all your computer stuff is on. Another review said that the reviewer interviewed all their pro friends, and that they'd never heard of an XQD card failing in the field, *ever.* And frankly, if I were a pro wedding shooter, since cameras are far, far, far more like to fail than XQD cards, I'd have *two* cameras with me, and shoot with them alternately. Maybe that's just me.
I admit that I'm a Nikon user and like Nikon ergonomics. And I'll freely admit that Canons and Sony produce photos that are just as good. I'm going to wait to see more in-depth user reviews of this camera, but I expect to buy one.