Molly, I'm glad you're so happy with your Z6! Good to know that you're not experiencing image blackout between shots. That must not be an issue with the Nikon Z cameras.
Eventually I have got to make up my mind and do whatever it is I'm going to do when it comes to moving forward with photography; I still have not come to grips about what new camera body I'd like to buy and although it would make sense for me to go with a Z camera since I have been a long-time Nikon user and have a lot of lenses, I still hesitate because I really am not keen on the idea of using adapters and right now Nikon is not offering a macro lens in the Z series. I'm sure one will come along eventually, though. A while back when I looked to see which lenses were compatible with the Nikon one of my macro lenses isn't, and I don't recall which now. That's annoying!
At the same time, while the idea of moving to Sony (right now I've got the NEX-7, the RX10 m4, the RX100 m6 and RX100 m5) totally and purchasing a FF body and a couple of their lenses is tempting, this would require selling or trading in my Nikon gear. So far (more than a year, actually!) I've been dragging my heels..... To date I have not laid hands and eyes on the new Z cameras or Sony's A7R III and A7R IV, and until I do that, not much progress is going to be made.....
You needn't worry about the FTZ adaptor. It works great. Flawlessly in my experience with a Z7 and all of my F-mount lenses. The only "gotcha" is that it won't AF with D lenses that are screw drive--like the 200mm micro. But for that lens I'm always using a tripod and using MF anyway, so it is a non-issue.
Nikon hit it out of the ballpark with the FTZ adaptor. Without it, the Z platform would have been a non-starter for most Nikon shooters. With it, it's really a question of whether the advantages of a mirrorless body outweigh the (minor, at least for my shooting) disadvantages.
Advantages:
(1) Smaller and lighter body than my D850
(2) Same menu system/UI compared to my D850
(3) Ability to use all of my F-mount lenses without any compromises (with the exception of AF with legacy lenses having screw drive AF where you are limited to MF). This also includes off-brand lenses like the Sigma 40mm f/1.4 Art which works flawlessly on my Z7 (actually better compared to the D850 regarding AF).
(4) Ability to use my Leica lenses with an adaptor (while there are some issues regarding IQ, the images are close to what I would get with my M(240) and they are noticeably better than what I got with my Sony A7R2 or A7R3. Not perfect, but very usable).
(5) Having focus points across the entire frame rather than limited to the center of the image when compared to my D850. This can actually be very important for some subjects.
(6) Significantly easier manual focus compared to my D850. My Zeiss 135mm f/2 is much more usable on a Z7 compared to a D850.
(7) The Nikon EVF on the Z6/7 is wonderful and I vastly prefer it to the OVF of my D850. It's awesome for manual focus, but also can show you if you've forgotten to change some settings from a prior shoot (why is the image looking underexposed or overexposed in the EVF? Oh it's because I changed something the last time I used the camera and wasn't OCD about resetting the camera to it's "neutral" state).
(8) While related to some of my above comments, being able to zoom in when using the EVF to confirm focus can be very useful compared to an optical VF.
(9) The Z lens mount can theoretically offer better lenses than the F-mount. For example, the 24-70 f/2.8 S (i.e. the Z-mount professional zoom) is significantly better optically than the 24-70 f/2.8E zoom for the F-mount. It's also smaller and lighter--which for me matters as it will fit in my "small" camera bag for walk-about shooting where the F-mount lens doesn't (on either the Z7 or D850). While this is relatively minor in the grand scheme of things, it does actually matter to some degree. If the Z lens was worse optically, I would deal with a bulkier load requiring a bigger bag. But the Z lens is both better and smaller. I'm hoping for something similar with a 70-200 f/2.8 zoom for the Z-mount.
(10) IBIS--this is nice to have. Your shutter speed may still be limited by subject motion (i.e. you may still need a fast-ish shutter speed to freeze subject motion, but the option of using slower shutter speeds for static subjects when shooting handheld is nice, regardless of whether you are using a VR lens).
(11) Easy ability to set a focus point and then recompose compared to my D850. Partially related to point (5) above. But I find it *very* useful in actual shooting.
(12) Eye AF--mostly works well and is better than what I could get on my D850. Not sure how I would compare it to my Sony bodies. I think overall Nikon's system works better and is more accurate, but I could be wrong as it's something that is hard to test. I really like the Nikon implementation that lets you shift to another eye (or person) via the thumbstick. This works well for me in actual shooting.
Disadvantages:
(1) AF for fast moving subjects--much has been written about this. In my experience it hasn't been a major issue. I took a series of pics at an amusement park last weekend and the Z7 nailed focus with rapidly moving subjects. Not perfect, but neither is my D850. But they aren't perfect in the same ways or for the same reasons. I think this is one area that Nikon could improve upon.
Possible I'm omitting some things from both lists. But I absolutely love my Z7. I prefer it to any of my other Nikon bodies or to my Sony or Leica bodies. It works really well, at least for my uses.