Things get much worse on a larger sensor.
One thing that may be forgotten that a sensor is not a flat piece like film but an optical package. It normally consists of:
- IR filter
- A dual layer of lithium niobate that act as beam splitters for OLP filtering
In case the Lithium Niobate is removed it would be replaced by optical glass with corresponding thickness, so I don't think the 7r will gain advantage in this respect.
That optical package needs to be include in the lens calculations. Biogon type of lenses are badly affected buy having an optical package behind the lens.
(check out page 12 of this excellent document: http://blogs.zeiss.com/photo/en/wp-content/uploads/2011/12/en_CLB41_Nasse_LensNames_Distagon.pdf
The differences between NEX-6 and NEX-7 may depend on different well design/micro lens combinations.
The Leica M has a lot of issues, too, but some of these are handled in software based on lens coding and estimated aperture (Leica calculates aperture from ratio of surround light and exposure). Leica doesn't use OLP filter and tries to use a thin IR filter.
Any comments on the 35 Lux FLE or 24 Elmar specifically? Is the 35 Lux totally clean and sharp? The 24 Elmar is great on the NEX-6, but shows strong shift on the NEX-7, so very curious about that as well...