OK I'll say it then. I'm not kidding about being kicked out of a FB group because I haven't drunk enough cool aid though...
So let me firstly give some background. I've shot Nikon DSLR's since the D70 came out. And quite quickly ended up with the more professional ranges. I shot weddings with a D3 ( which I pre-ordered because I couldn't put down my D2x ) and a D700 as backup for quite a few years, but eventually wound up the business and sold all my bodies and moved to just a D750. I kind of drifted away from photography then due to lack of interest. When the Z6/7 were announced I started to pick up my D750 again and decided to move to a Z6. So I got the Z6 very early after the pre-orders.
So I got my Z6 and mid May I was asked to shoot a friends wedding in Cyprus to capture more candid stuff as they'd only paid for a basic photo package with the destination wedding package. So I shot this nearly exclusively on the 105/1.4 with V1 firmware. Quite frankly it was awful on V1 FW with lockups and focus all over the place but I managed. But after enjoying it, and getting loads of positive comments I started to consider getting back into the wedding business. So I decided I needed to shoot a lot with the z6 to learn it, assuming it was me.
Oh, let me also preface this by saying I have always used back button focus and AF-C. I've always shot every SLR since the button was there.
Now V2.00 came along not long after and everyone was raving about it. So let me get this one out of the way first... But keep reading after honestly. I ran home, uploaded V2.00 and immediately tested eye-af and... urggg, eye-lash af
Now it's not a often you expose it badly by shooting close with a 1.4, but I could see it with the 24-70/4 lens just as easy. You have to stop down a fair bit to not find it noticeable. Interestingly I've seen loads of youtube videos trying to claim it's fine, but in most of them the examples clearly show the same thing. Anyway you can cope with that, shoot at f8 and it'll all be fine haha but eye-af gets confused quite a lot. Have people in the background, or people at different distances from each other, and quite often it seems to get badly confused. So I don't use it, it's turned off completely.
Dynamic-AF I have seen issues with. So there is no 3d tracking or anything similar, so dynamic af seems ok if the subject isn't moving towards or away from you, but I've noticed it can get confused easily by things in the background when a subject is moving towards or away from you. I was shooting a 5-a-side football match by professional footballers for a charity thing, and it often seemed to get confused and focus on something behind the subject, even though the focus box in the centre was on the subject.
Now this isn't a speed issue. I don't subscribe to the idea that the Z6/7 are not fast enough, some claim it's no good for sport because it's too slow, it's not slow. It's that it seems to get confused, and if you look carefully you will always find something in sharp focus, just not what you were pointing it at.
So I tend to use single point mode exclusively now as it's the most reliable. But even single point in AF-C has issues. I've had a couple of instances where it point blank refuses to focus on the target. I was trying to take a photo of a robin at the Eden project, sat in a bush right in front of me, the focus point completely on the robin, but it wouldn't focus on it. In fact it focused on the things through the bush. I even put my hand in front of the lens, focused on my hand, then back on the robin and it did the same. Maybe it has a Robin phobia. haha
But more often that not I find some shots just not in sharp focus. Close but not in focus. My main subjects tend to be people ( but not models ), who don't hold position while you take a photo, they move a little bit and often when you look at the photos they're just not sharply focused. Now if I use AF-S, it gets it right pretty much every time, but I don't use AF-S if the subject is moving as it won't work.
So for me, it's not that the speed is lacking, it's not that it can't be accurate ( it is in AF-S ), it's that there are bugs in AF-C mode algorithms. I also have a suspicion that the AF area is too large, and I'd love to have a Z7 to compare as that has smaller AF points because it has higher resolution, and actually when you look at the size of the sony points they are much smaller. The Z line just isn't as reliable as say a D750 on AF. I'd say the Z6 is a lot faster to focus than the D750, but not 100% reliable at the same time.
So switch to Sony I have people tell me. But I got the chance to borrow an A7ii and quite frankly I hated it. The feel, menus, button and everything about the physical body I didn't like. But the AF was fantastic. I haven't tried the A7R4 or an A9 but they are supposedly better. But I wouldn't switch.
So what I'm doing is putting my faith in Nikon that they will fix it. There's a new FW update coming at some point for the raw video, I'm hoping this will have AF improvements too. In the mean time, I over shoot. I over shoot a lot. I use bursts of shots and then I end up with less missed shots as pretty much every time you can ignore the soft image as you have a sharp one to make up for it. I've switched to nearly all Z line lenses, because they're stupidly good, and just waiting for the AF performance to catch up a bit.
Edit: Sorry that was a lot longer than I planned it to be, bit of an essay sorry