[Brightcolours]

You're welcome, interesting to see your results so far.  

Thanks Dave, I will be comparing them more to get to know them.

The Pentax K-versions are a bit less dear than the A-versions due to the lack of auto-aperture, so quite suitable for adapting to EOS mount.  I was going to suggest the Voigt 58 as well (f/1.4 on 58mm is about the same DOF as f/1.2 of 50mm) but also surprised that it's not available in EOS mount!

I read that the K versions have lesser coatings, I wonder if for the rest they are optically identical?

[Brightcolours]

Both lenses have a too narrow barrel, whether that is on the front or the back or both I do not know (not knowledgeable enough in that field), but my guess is mainly at the back. They make cat eye shapes on bokeh discs almost over the entire image except the center. 

 

The Canon FL 55mm f1.2:



Some outlining can be seen too.

 

The Nikkor-S•C 55mm f1.2:



Similar outlining, and a ridge around part of the back element (seemingly there as part of holding the back element in place) is visible in the bokeh disk shape.

 

Again, the colour difference between the two lenses is apparent.