FWIW, here is a quick synthesis of my experience with a NEX 7 so far. For reference, I have shot thousands of pics with a NEX 5, hundreds with a C3 and thousands with a 5N, all with alt glass, before getting the 7.
There are at least 2 WA that work fine of NEX 7, alas neither of them cheap: the Leica R 19mm V2, which was expected, since it is a DSLR lens, and the totally unexpected LEICA WATE. The WATE shows no softness issue even at 16mm even wide open, even in the extreme corners. It just works, period. This shows that lens construction is much more relevant than FL. If this one lens works, then other similar designs in terms of geometry and placement will work, irrespective if it is an ultra-expensive Leica or not. Careful examination fails to show any camera issues, which proves to my satisfaction that the camera itself "can" work just as specified providing a lens is mounted on it that suits it.
One WA lens shows mid-to-strong colour shift, which otherwise works fine on the NEX 5N, the Zeiss ZM 18mm f:4.0. However, it cleans up very nicely with Cornerfix, and the result fails to show any issues (test shot at f:8.0, I have not yet tried wide open, but will before deciding to keep and shoot the ZM 18).
One wide-ish lens showed mid-to-strong colour shift, which otherwise works fine on the 5N: the Contax G 28, and I have not been able to clean it up with Cornerfix. I believe that the result, even if rid of colour shift, would also display unacceptable softness issues. This is a Biogon, symmetrical design, and likely the most problematic construction for the NEX 7 to accept, since even the much more tolerant NEX 5N is marginal with the otherwise brilliant ZM 25 Biogon.
I briefly tried the Leica M 28 Summicron f:2.0, and got clear but mild shift, but did not try to clean it up, as I had no interest in buying that lens.
I tried less wide lenses, and did not come across any trouble at all: Contax G 45 and G 90, Leica R 35-70 f:3.4, Leica F 60 mm Makro.
For reference, the "easiest" way to see shift is shooting straight into a blue sky. Second best is a white or light gray target. In my experience, it is possible to "get away" with even severe shift if you are ready to work around it. I sold a Contax G 21, a fantastic piece of glass, which I couldn't get to work even on a 5N. Even cleaned up, I got mush in the corners, and I am far from a "sharpness-über alles" ayatollah. Well, that guy whom I sold it to has been showing awesome pics from it and his 5N....
In summary, the NEX 7 is a camera that can work as specified and advertised, and its IQ is awesome. BUT, to get there, one needs to understand that (1) viewing a 100% crop of a 24Mp camera is a significantly higher magnification than with a 16Mp camera, and thus a much harder test, and (2), the higher the pixel density, the more it will show any weakness in the shooting itself. For example, the 7 clearly shows the difference between critically sharp and hyperfocally sharp, which the 5N does not. It also requires that I use much higher shutter speeds if I am to avoid seeing motion blur. When shooting from the waist, on a good day I can use my 5N down to 1/3 of 1/focal length. I have not been able to get lower than 1/focal length with the 7, and even that was not with a great keeper rate.
So the 5N is a really great ultra-small platform for alt glass, delivering very good IQ pretty easily and without fuss. Perfect for shooters who want a platform for a variety of existing glass, or use it as a "take-anywhere-shoot-any-time-and-any-place" camera.
That, the 7 is not, and it will punish you for trying. BUT, as a small-ish platform for chosen glass shot carefully, it will produce IQ that is on a par with the absolute best DSLRs, with the exception of what a FF sensor can do (very thin DOF).
I rest my case (and the pot)
