Not to change the subject too much but I'm curious about the "meh"-ness of your 100-400. I've tried three of them; two of them, including the one I ended up with, very impressive including with the teleconverter, the other pretty dismal toward the long end within about 30 feet as the sweet spot gradually shrank to just a small sharp area in the middle by about five feet. (The other "good" one had a mechanical fault).
I've seen a number of different 70-200/2.8 S lenses and none has what the F-mount E series one has close up at the long end, though the S 70-200 is a bit better than the F-mount at the short end, not least because of closer focusing, and it's just generally more flare resistant in the bright than the E.
What's been your experience with those two?
Mike does not have the Z 70-200 f2.8S.......yet!
I have had the 70-200 f2.8G VRII, then the 70-200 f2.8E FL VR and now the Z 70-200 f2.8 VR S. They were/are all excellent in their own right at their time in history and there is no doubt the 70-200 f2.8E FL VR is a superb lens. However, it is slightly overtaken by the new Z 70 200 f2.8 VR S, IMO. It is simply idiotically sharp wide open, better than many primes, and basically is no better stopped down as I don't think it could be sharper! It is sharper than the 70-200 f2.8E VR wide open and stopped down. However, important as sharpness is, a lens's worth is not and should not be measured solely on sharpness! It is the overall IQ of a lens that really matters and again, with all the iterations of the 70-200 f2.8, they have been superb as far as overall balance of IQ - bokeh, color, CA, etc but the Z 70-200 f2.8 VR S is best of all. One might have a slight advantage here, the other a slight advantage there. However, the Z 70-200 f2.8 VR S seems to have achieved the best across the board yet.
This is just my opinion and what appeals to me about the Z 70-200 f2.8 VR S. Of course, YMMV.
If Mike ever gets the Z 70-200 f2.8 VR S and if he also thinks it is better than the 70-200 f2.8 E FL VR, he will be able to describe why it is better way better than I. He has the gift of being able to describe a lens's ability so as you think you have already used it even if you haven't.
(The 20/1.8S has been great for me, talking of on-topic, though I think one corner might be a little behind the others. Overall clearly better than any F-mount wide angle I've used, note that I've not tried the Tamron 35/1.4 or Nikon 28/1.4E)