Glad you reopened. One thought I had in reading your responses to the input you've received is, "I wonder if he realizes the significant difference in size and weight for a FF system of the same capability FOV-wise?" You've talked a lot about your desire for more image quality. That's certainly understandable, but the gain in absolute image quality (which really only means "how large a print I can make" - not image quality per se, if that makes sense) comes with a price in lugging around larger and heavier gear. I have both a FF system and a mirrorless APSC system. While the FF does have the advantage of being able to print larger at "the same quality" as the APSC system, I find that my ability, desire, and willingness to explore a subject is greater with the smaller, lighter, more versatile system. I often end up with more interesting images from a creative standpoint with the smaller, lighter system.
The point is, you may have been benefitting from this w/ the EM-1 w/o ever realizing it. Give that some thought and perhaps rent a FF and a few equivalent lenses and go out and play and see if you've "lost something" in the process even though you've gained something in "absolute" IQ.
I think many of us are being refreshed, creatively, as we've started using the compact sysem cameras. I know it is true for me. I'll keep my FF gear, and reach for it when I "need" that next increment of IQ for a specific situation. But I can tell you that it is happening less and less often as time goes by. And I'm enjoying photography more and more with the smaller system. And, if you really want a shocker IQ wise, get your hands on a Sigma Merrill camera and make some big prints from that little brick of a camera. But that's a whole different discussion from the one you started.
Rand