I need to do more testing. I have found animal eye-af doesn't work 95% of the time with my Black Labrador puppy, I don't have anything else to test it with at the minute as we found a home for the stray kitten we had living in the garden.
I've only had chance to try human eye-af briefly on my daughter ( who wears glasses as well ) and I can say that the eye-lash-af effect is greatly reduced, but possibly not completely eliminated. I haven't had the chance to try this outing better light though as with the short days and awful weather over the weekend my usage has been significantly restricted. From my use so far I'd say yes it's better than the Z6, but how much better I haven't determined. So far it feels as good to me as the Z6 was with D8 turned off. I never really used eye-af or wide area on the Z6 anyway honestly.
In my personal opinion right now, I'd probably think about waiting until the next FW release for the Z6ii to pick one up if you already have a Z6, yes I think it's better, but maybe not enough to justify the upgrade cost. But I reserve the right to change that opinion once I've actually managed to get out with it more