As promised here is review of the image quality of the Promura Gekkor 135mm f/1.8. I am not going to pretend to do an in depth or rigorous examination of the lenses image quality, but this should give a rough idea of what to expect of such a lens.
For my bokeh test I pit the Promura up against the Vivitar 135mm f/2.8 lens to see how it stood up. All the photos where taken on my 24MP Fujifilm X-T2 and I also used a Zhongyi Len Turbo II focal reducer to approximate the bokeh you can achieve on a full frame sensor. I have also linked to the full resolution JPGs for pixel peeping.
Full Res JPG
I think the last image really tells the whole story. The bokeh on the Promura is noticeably smoother. at the same tile the sharpness is clearly with the Vivitar.
Like the bokeh comparison I tested the Promura Gekkor against the Vivitar. I won't go in depth here. I'll just let the image speak for themselves.