I was not happy about using an adapter for my f-mount lenses.
I find myself coming around to the idea. I was having trouble putting my finger on it exactly. But I think it comes down to two things:
Simply, the FTZii does not look like it gets in the way like the FTZ did with its tripod hump. If I leave FTZii adapters permanently attached to selected f-mount lenses, I will not even notice that they are. Of course I have to buy quite a few FTZii adapters.
This one is a little more complicated and it took me a while to wrap my head around it. But I have often said that the camera is just a photon detector. It is the lenses that matter. It is a substantial exaggeration, but it ensures that I never lose site of what really matters to me.
Prior to the arrival of the Z9, the best "photon detector" that I could put on lenses like my 28 1.4E and 105 1.4E was my D850. Sure the Z7ii provided equivalent IQ, but the focus was better with my D850. The Z7ii actually focuses pretty well, but the ergonomics were clunky. One of the most used buttons on my D850 is the focus selector. Sometimes I leave it alone, but when I want to change it I want it to be quick and seamless. On my Z7ii, I have FN2 assigned for that, but it is awkward to use the command dials while depressing FN2. On my D850, my left had is on the focus selector and my right hand is on the command dials. Not clunky - natural. And on my Z7ii, FN1 is assigned to subject tracking. So I have no FN buttons left that I would like to assign other functions to.
With the Z9, it occurs to me that I will have superior ergonomics and superior focus to any camera that I have ever owned before. Especially with 90% focus coverage. And with my Z7ii I felt that my f-mount lenses were diminished, it is obvious to me now that my 8-15 3.5-4.5E, 28 1.4E and 105 1.4E, lenses with no corresponding Z-mount counterparts (I find myself with 2 20mm 1.8 lenses now), are now better than they were before. My 14-24 2.8G, 24-70 2.8E and 70-200 2.8E are also now "better". My only quibble is the 400 2.8E and the 1.4, 1.7 and 2.0 TCs.
Thom pointed out something in his interview with Paul's camera which really resonated with me. For you PF junkies out there (I am not one of them) the roadmap seems to suggest that there will be a 300mm PF (current f-mount), a new 400mm PF, 500mm PF (current f-mount) and a 800mm PF. Wow! Slap a couple of FTZii adapters on the 300mm PF and 500mm PF and forget they are there. That is a wicked lightweight telephoto line up.