Using a 35mm lens of similar quality on the NEX-7 seems like a much more real world test, doesn't it?
In the end, photographers care about perspective and crop, so they will often use a 35mm on the NEX-7 to replicate the framing of a 50mm.
The very wide array of lenses available for the NEX platform is one of its best value, so it should be easy to find a good 35mm, shouldn't it?
Of course, there is no reason to think that the NEX-7 has sharper pixels than, say, an A900 so you might as well do the comparison between 2 FF cameras which will enable to use the exact same focal lenght, if not the same lens. There are many amazing 50mm lenses for all the FF cameras, even if the A platform is probably not the one with the widest offering.
It is very easy to convert a Leica R 50mm lens to F mount for instance.
Cheers,
Bernard