Upload & Sell: Off
Well, the 50MP looks plenty sharp and contrasty in the corners too...
I'm seeing two entirely different types of comparisons to be made to truly compare the usability of the MB adapter.
1) How good is the adapter with lens "X" compared to using the lens on it's native FF format?
2) How good is the adapted lens "X" compared to the native lens "Y"?
All comparisons in category 1 is a losing battle from an optical PoV. All the aberrations in the adapter have normal, natural polarities, meaning that anything and everything you throw at it from a native lens perspective is going to get worse (than in native format). What's left here is the (maybe) more compact physical format of APS, and freedom of choice. Either with 0.7x speed adapter or no-glass adapters. All lenses become two, seen with this perspective - assuming that you have a no-glass adapter too of course...
Comparisons in category 2 are more relevant in this case. Is a bog-standard 50/1.8 used together with an MB adapter better than using a 35/1.4 on a no-glass adapter? For what lenses is this true?
If the answer is "true" in a wide variety of category 2 cases, then the price for the adapter is very easy to justify. A trio of 35F2.0, 50F1.8 and 85F1.8 quickly becomes the very expensive trio of 24F1.4, 35F1.2 and 50F1.2.
One lens I'd really like to try is the old Nikkor 35-70F2.8. It's compact (large lenses are totally useless for me, why bother? I have FX cameras that do that work better in all cases!), and the range suits a "normal use" walk-around standard lens. It would be like having a native 24-48F2.0 on a NEX, and the base optical quality would hopefully be very good. The adapter would from everything I've seen so far be very suited for most normal zooms, that usually have an exit pupil distance smack in the middle of the MB adapter comfort zone.