(This post is from an email conversation with a friend. I thought the content might be useful for others.)

I like the Z7 pretty well, but it’s no D850.  I love the size and the EVF is good.  It’s a lot quieter, too.  And I seldom do video, but the Z7 is 1000% better for that than the D850.  Focus during video is SO MUCH BETTER!

But my experience with the battery life is right in line with the CIPA estimates at 350-400 shots per charge, though others have claimed a lot more.  (I wish I knew how!)  And the AF for still photos is poor to horrible in low light.  Also, having to wait on the thing to start up either from sleep or turning on is maddening, being so used to just leaving my D850 on all the time and it being immediately ready to view and shoot.  The delay is only a couple of seconds, but it’s excruciating.  (Trying to keep the battery life up I turn it off often.)

So for me it’s not a replacement or even close to one.  But it makes for a good travel camera (except in dark cathedrals) and is a great(!) camera for video.

I’ve always wanted a D750 for the smaller size/weight but haven’t used one, and I also don’t know what all you like to shoot.  The Z6 could be a good choice for you but might not, depending on your use cases.

I thought about going with the Z6 but didn’t want to lose the pixels that I’m used to having with the D850.  I have 24×36 and even 32×48 prints hanging on my wall here in my office and many of them are photos I took while traveling.  Since I’m not that great a photographer many times I end up cropping quite a bit to get the image I want.  I need the pixels to have the enlargement potential if / when I get something decent.  Otherwise I definitely would have gone with the Z6.