In Guide to Leica I explore* the performance of the 18mm f/3.8 Super-Elmar-M on the Sony A7, which lacks the micro lenses of the A7R.
This finishes out the M-lens range in addition to the 21mm, 24mm, 35mm, 50mm, 75mm, 90mm. I still hope to obtain a 16/18/21 Tri-Elmar-M. I might do further work on the A7 later, but I don’t expect the results to be materially different in the wide angles from the 18mm.
* Leica M and Zeiss ZM lenses are always reviewed in Guide to Leica, regardless of camera body used, an organizing principle that holds true regardless of how many new mirrorless cameras evolve. Ditto for DSLR lenses: lenses stick to their native publications. Cameras are accessories to lenses.