I have the same question. I mainly shoot portraits of my kid. I start out with 50mm F1.4, then I upgraded to 24-70L, but I found out F2.8 is not fast enough indoor, and also, the bokeh is not good. Now I have a 85mm F1.8, and 135mm F2. The reason I get the 135mm L is because I cannot justify the price of the 85 L .. it is tooo expensive. Even a used MK I cost about CAD$ 1400. And I wonder if it is THAT ($1000) much better than the 85mm F1.8, and also wondering how would it compared with the 135mm. I mean .. with a 135mm, the longer focal length isolate the subject more. But the 85mm @ F1.2 will have a more blur background? It would be nice if someone who has both lens to take some test portrait to compare the bokeh between 135mm @ F2 vs 85mm @ 1.2 with the same composition.