Time to have a bit of a test. My question still is electronic shutter vs Mechanical shutter.
I set up on a tripod for constancy but with a monopod in mind.
My tripod is a medium weight one and I left the quick attach a little loose so the camera could flail around a little on its own hopefully to exaggerate shutter shake.
The top 2 rows are with the shutter set to 12 second delay and SR off by default.
The bottom 2 rows I fired the shutter as usual with my finger as you would with a monopod.
So SR was on here.
I feel the results vindicate the view that shutter shake is limited to the 1/60 to 1/200 area.
The stand out shot though has to be the hand fired 1/50 mechanical shutter SR=on. The fact that it is better than the 1/100 next door is a good example of SR being a little hit or miss.
My own conclusion here is that a little trust (and hope) in SR outweighs going overboard with Iso.
So the biggest pity I feel with my Falcon shot is that I had the camera on Electronic Shutter.
The Magnolia flower stamen crops are 300 pixels crops from the centre of the image. I had to downsize about 50% to upload the test to here. I used the 400-600 mirror @600mm on the K-1. I did not change focus through the test. Images saved as jpg camera default.