Dirk, you're the only other person I've seen with the I-series 50/2, which I don't think is a popular lens.
I like mine a lot. But I am a dinosaur. I just love the haptic of metal and the aperture ring like in the 80ies.
Recently I’ve acquired the 100 macro and may in fact let the 85 go as it’s too close and 2.8 is fine in fact
The Sigma 100/2.8 DG DN Macro lens is a beast. Very big and very heavy. I did not include it because I thought noone would see it as an alternative to the other short tele lenses?
If you do portraits and want to have eyes and nose in focus, you need F2.8-F5-6 depending on your distance to the person.
F1.4 is cool, if you are further away or if you really want to "nail" the eyes. I have not shot yet with my new 85/1.4, so I can not comment on image quality vs. my Lumix 85/1.8 or 90/2.8. Hopefully next week the weather becomes significantly better...