@tablejockey
The issue with the golden ratio for which (I sense) you advocate is the extreme confinement of the space (disregard dedicated or not) down to almost near-field listening. Take my room as an example, with the golden ratio rule, the listener is literally 6 ft 3 inch away from the speakers in a 14’ x 18’ size room. Why do you want to confine your listening space down to a 6 ft equilateral triangle, equivalent to 7% of the 14’ x 18’ room space? I sit in the Ikea Pong chair with ottoman and my feet are half way to the speakers. That is insanely ridiculous. I do not enjoy. No one will. Not to mention the SS is not as good as the positions I end up with using LOTS. Have you ever tried yourself I wonder?
To answer your second question, the positions I end up with as shown gives me the widest SS and a bit less SS depth compared to 5 ft setback from the front wall. The center image is focused and instruments and vocal are well separated within the SS.