I did an informal test with the 100-400mm lens and all is ok. I did on tripod with iS off, on tripod with IS on and handheld with IS on.
Not really much difference at all but if I had to pick a winner I would say handheld with IS on followed by on tripod with IS on. Surprising how slow the speed can be and still handhold- 1/80 seconds is still good. I think there are more particles in the air in Oregon which affects the clarity in the field. And clarity is affected by how far away the subject is, especially here in Oregon. I should have done the testing before I posted the question here in UHH.

Agreed. That was one of my considerations when I replaced my Sony a6000 with another brand.

Nice video!
For the OP there are also other videos that can be accessed via the link to give ideas of other approaches.

Generally mirrorless camera batteries are smaller and run a lot of electronic functions. There are ways to conserve power but when I had my Sony a6000 I just accepted the limitation and bought more batteries. Fuji and Panasonic batteries last longer but none compare with DSLRs.

Beautifully done!
But the 200-500 mm lens weigh 4.5 pounds on its own! Guess weight is all relative. Now the new Sigma
100-400 mm weighs 2.5 pounds and costs significantly less. Wonder how it compares.

Ah come on, tell us what you did/didn't do.
I've had that happen to me with the Fuji X-T2 more than once actually. The speed is set/controlled by a dial on the camera which in turn has to be changed from that dial. Was it that simple?

It's amazing where roses can thrive! I see some of the nicest roses in front of the most derelict houses.

Nice sharp, colorful shots. A super start. Birds aren't always where you want them and you can't always control the background or get closer. If you can, cropping your shots closer and opening your lens wider might help your birds to stand out.

He is growing up. What does he weigh now? Gorgeous dog, lovely images.

I bought and returned the Fuji X-T20. It was too small and I have small hands. I replaced it with the X-T2 which was a much more comfortable fit. Both cameras produce excellent images.

The Peak Design camera strap can attach to the camera connections OR one to there and one to the camera tripod plate. Your choice. The 2nd method distributes the weight well and stops the camera from swinging. With a long lens you will most likely be connecting to the tripod via the lens collar and not to the camera tripod connection. So all is good. Check it out.

Bill S. by the time we get this all figured out the camera will be obsolete :) And it would be interesting to do a comparison between the two cameras. I'll PM you when I find something out here.

Clint and Bill-
I have some images I shot for sharpness when I first got the camera and lens combo. They are on an external drive (somewhere)- think I can find them and do a comparison shot. I have been pretty happy with this combo and hope this is just a passing concern.
And Bill B. The software upgrade was to correct the shutter shock by putting the camera on "auto" shutter mode which automatically shifts it from electronic to mechanical shutter between your aforementioned range (which you probably already knew). I rarely ever shoot anything between that range but I put the shutter on auto anyway.
Thanks for all your tips.
But anyway before I jumped into tests I just wanted to know if anyone else had concerns after the upgrade.

Raw plus fine JPEG.
I did a reset of the camera and reentered in my preferences. Interestingly enough when I went to shutter type it was totally grayed out (before I did the reset) - after I did the reset I was able to set one of the options which I set to the new "auto" choice. Other than that I didn't see any peculiarities.