I sold my Loxia 50/2 and I am waiting for Loxia 35/2 for test. My note about pro photographer and out of focus shots is rather sarcasm toward artsy look, that some photographers try to force either via de-focus or via post processing (or other formal technique). Key to my point of view is – formality. I literally hate to see, when photographer is trying to hide lack of idea and/or content behind fancy image look.
But focus is one of the most important creative tools in photography and being able to take full control of it is more than pleasing experience, that no other E-mount lens can deliver.
To answer your question, difference between focus by wire and mechanical coupled one is hard to express by words, and even harder to define, where that can become creative limit. In practice, I found much easier to make fine focus adjustment at wide aperture, let’s say at models eye iris, than with AF or focus by wire. Hope that makes some sense to you…
Regarding some shots being darker than other at the same aperture, we would have to compare shutter speeds too at the first place and also to consider often changes of lighting in exterior as well as light fall off, affecting camera exposure measuring. There are simply too many variables to compare lenses on a live model shooting outdoor in terms of technical performance. Only possible comparison is thus subjective – you either like one of the shots in the series more or you don’t.
That’s why my review has several situations including few controlled ones for some technical (objective) evaluation (however useless those test charts are).
Honestly, any of those lenses is far beyond my photographers skills anyway.