Dr Pc Fix, you have peaked my interest and must ask the reasons for a lens with such shallow depth of field. I have a 55mm F1.2 with a FD mount, the glass is huge compared to my 50mm F1.4 lens. Being a EOS mount with a USM motor to drive the optics, the weight will go up, add the cost of a pristine 50mm F1.0 L lens would also cost a quite a far bit. Now for a little research I did on Youtube, check out Matt Granger. He compared one to a 50mm F1.2 and a Nikon 50mm F1.2. Canon does not make a new 50mm f1.0 L lens (this lens was designed for use on a full frame camera) and a second hand one goes for between 4500 dollars and 8 thousand dollars, so if you are still chasing one this Youtube clip is worth a look.
No other 50mm lens can isolate a subject from its surroundings as strongly as can this lens. This lens lets you make the background just go away. Used on a modern quick focusing camera such as the EOS RP you have a recipe for some eye popping extraordinary candids.
Have you used the more modern 1.2L? They are 1/3 the cost and sharper wide open. From the few comparisons I saw of the two its hard to really distinguish images shot with the two of them.
