relative size difference m43/APS/FE

That's a stretch. I use boxes with lenses attached. Noted which ones, Noted a similar result. Why these two setups in the first place I can get into, if you wish. I wasn't sure if you were genuinely asking.

Well, it all comes down to time, money, pragmatism and pride.



Time. It marches on.
I used Olympus gear analog, loved it. Slow to digital, very expensive. I still have and use my 4/3rds gear. The E-5, I was really happy with. If Olympus released the E-7 with the upgraded sensor and processor I would have stayed.
In light of our recent conversation, I HATE processing, not my thing. The out of the box images from the Olympus processor renders far better than I can. I've only been dealing with RAW files for the last few years because I was so unhappy with what I was getting from the Sony's. When I finally saw what the CCD sensor from my a100 was actually capturing and the crap the image processor was putting out, my jaw dropped. With Olympus it's the other way around. The RAW's are Meh, but it comes out NICE.
I LOATHE the electronic view finder. My EM-1 has remained mostly unused 'till this year because of it. I have a set of a99's and a77's but prefer the OVF of a850. I am learning to tolerate the EVF's.

Money, It all costs something.
While waiting for the a77III I hesitated. fumbled. A-Mount discontinued, E-Mount expensive and for me, not ready for prime time. I scrambled and stocked up on A-Mount and started another look at Olympus. The Body isn't the only expense and I was well provisioned in legacy gear for the change back.

Pragmatism. I'm closer to the end of my photographic journey than the beginning and was never more kitted out.
I finally went with the Olympus OM-D EM-1 Mk2 for the in camera processing of HDR, Focus stacking and High Resolution images. It makes my workflow easier. At least the little I still do. I've been backing away from weddings; permits, insurance requirements and "Hollywood" expectations. Realty listings want Drone shots and 4K video now.

The Olympus IBIS is good but if you're more than two cups of coffee shaky... it's not magic. I've never gotten the headline performance. I think the person who rated it was an eye surgeon. I found it best set to IBIS auto and sequential low. If you try for a single use the 2sec. timer.
The IBIS also has a problem. Movement beyond camera shake. Sway, Shiver, Subject movement, it will result in blur or loss of sharpness. All that is smoothed out in video but it's still there. Good light is really good. I rarely run over ISO 1000.
The Sony's I like and use for different reasons. OVF - the a850 is a joy to use. The a700 also. EVF - The Sony EVF's have been functionally better for me with the a77/a99. The Olympus EM-1 Mk1 gave me vertigo, still does actually, but my time with Sony seems to have lessened the effect. Not a problem with the Mk2 but my concern returning to Olympus.
The a77 Mk1 is my favorite Sony camera for business and pleasure. If it had an OVF it would be perfect. The a99 as a 10MP full frame camera it is awesome, 24MP less so.
Edit: TMI

   

Edited by LAbernethy - 11 December 2021 at 12:34