In my analysis versus the OM-1 I did not think either "rolling shutter" or "limited buffer" as important. I liked the APS-C 32mp sensor size better than the 20mp sensor size of the OM-1 and I liked that the Canon 100-500 F/7.1 was a pro lens and the Olympus 100-400 F/6.3 was not. I liked that both have an 800mm full frame equivalent reach.
I liked that the OM-1 was considerably more compact and more than 1/2 pound lighter. (The OM-1/100-400 is less than 4.5#, the R7/100-500 a bit over 5# and the D-500/500pf a bit over 5.5# on my scale) I also liked that the sensor was a modern stacked BSI sensor.
I thought that BOTH would be a significant upgrade to my D-500/300pf/500pf rig.
Now, 4 months later I see that Nikon is continuing to move away from DX cameras and lenses and seems to prioritize primes over replacing the 200-500 zoom. For Nikon to produce what I need they need a D-500 replacement and a newer zoom. Neither have happened yet.
That 4 months has been critical to learning the new system in advance to my bird photography trips that start in November and stretch to May. What have I learned?
When shooting a cropped camera with a lens that has a high f-stop the effective f-stop (f-stop x crop factor) goes through the roof. (11.3 on the R7/100-500, 12.6 on the OM-1/100-400 compared to 8.4 on the D-500/500pf). I now really need to pay attention to proper exposure and actively change the exposure compensation in the field. I also need to use one of the new software offerings to suppress noise and to only sharpen the subject. On the plus size the WYSIWYG EVF makes paying attention to proper exposure a piece of cake. (I did not find the difference between the OM-1 and the R-7's EVF resolution a big deal.)
I found that the Olympus 100-400 F/6.3 is a fine lens. The enhancements that go into an Olympus PRO lens are not important to me because I don't shoot manual focus. I did pick up an 300f4 but the zoom is my goto lens.
What would I recommend to a Nikon D-500 wildlife shooter? Either pick one.
Regards,
Tom