[JJ_SO]

That wasn't intentional. And no, I don't think a breathing workshop would have helped. Nor would IBIS (or VR)

 

Especially for you: Nikon D7200, AF-S DX 16-85 VR at 52 mm and f/7.1, ISO 400, 5 sec exposure. ND 3.0 filter and Leica tabletop tripod with tiny Markins ballhead.

 

I'm not sure what your point is by now, mine was just: shots like this would require a little less effort with a camera that could do really low ISO. I wouldn't have to remember taking the ND filters (the right sizes), wouldn't have to compose the scene first, focus, do a test shot, then mount the filter, adjust exposure and shoot. With low ISO, I could save some time and (most notably) still have a usable viewfinder image.

 

And the shot is where...?

 

My point is: Instead of stretching a modern sensor beyond it's possibilities, I rather prefer a soft- or firmware solution, keep base ISO at 64 and also the max ISO - I'm rather afraid, your highly specialized ultra low ISO sensor would do just these low ISO pretty well and suck at "normal" ISO like the Sigmas do. No free lunch...

 

And if you (or I) need a second body with a more universal sensor, all the "don't need to think about or transport ND filters and their holder" benefits would be lost.