I've revisited this question of how similar (or otherwise) the sensors in the a77 and NEX-7 are. This time I used the 16-50mm f/2.8 kit lens from the a77.
I've done a series of comparisons from ISO 100 to ISO 6400. I've left out ISO 12800 since its quite difficult to see anything in the mess of noise that those files produce. All images were processed in the same way using the default Adobe Camera Raw settings in Photoshop.
Clicking here or on the image below takes you to a folder on flickr, with all the (full-size) comparison shots.
Each image has a metadata screen shot attached to it, so you can see the settings. I used f/11 throughout. By clicking on the comparison shots > Actions > View all sizes > Original you will see a full-size jpg version of the file. (Saved at jpg. level 8)
Hopefully, even with flickrs rendition of the images, you should be able to see that there is a (very slight) difference in the files. Once again the NEX-7 files are slightly softer, slightly less noisy and also slightly darker. You will see from the metadata that the shutter speeds are pretty consistent between the cameras, with one or two exceptions.
It doesn't prove much, and for my uses, mostly at low ISO settings I have no problem with either. On the NEX-7 I will be using lenses like the Zeiss 24mm and m-mount lenses anyway, which will eliminate that slight difference in sharpness.
By using the 16-50mm lens on the NEX-7 with the mirrored adapter, I think I have taken the possibility of the a77's translucent mirror affecting the results out of the equation, and my only guess at what is causing this is either a slightly stronger Anti-aliasing / low pass filter in the NEX-7 or a difference in the processing engine. Another possibility, I suppose, is that the mirror a-mount adapter is affecting this.
And while it may be of interest to pixel-peeping geeks like me, for the most part its not that significant, and certainly doesn't affect my opinion on either camera. I've more or less decided (well for today anyway!) to keep both the NEX-7 and a77, and ebay my 5n's and Samsung NX200. Ann is now trying out the GX1 to see if she prefers it over the GF3 for a go anywhere camera, and I'm hoping that she will opt for that, since I'd love to keep that around, and even if I don't use it much (since it won't be mine!!) it would be good to know that its still in the house.