I've been using a6700 for a while, but not anymore because evf is so small or unconfortable to see througt it... I just can't get used to it. I really prefer the a6500 evf. It's rare how can they make worse that kind of essencial parts of the machine.
The big grip of the 6700 is nice ergonomics for holding a tele lens wich was one of my needs for nature stuff... but it's a bigger camera beside the 6500. So the size of 6700 is also like a downgrade when you look for a smaller and ligther machine in the land of aps-c cameras.
On video specs you can think 6700 is very powefull with the fx30 sensor but again, it's not the same because on a6700 you don't have 120p with all-intra codec 600mbps... Only xavc s and hs -h265-... So another dealbreaker for me, cause i want to capture wildlife in slowmo but i don't have the unleashed sensor power.
Of course the sensor and video specs improvement beside the older aps c generation is huge in 4k land, where the a6500 have his limitations, but again you are paying almost two 6500 for one 6700...
About AF i don't notice impresive improvement between diferent sony cameras.
I've been using sony for a while, nex5r, a6500 and recently the fx30, zve1, a7s3 and 6700 in nature, mainly on mountains and in a forest recording different animals and birds between trees and leaves in very busy frames and manual focus is my best and only friend. I can't see an improvement on that challenging conditions between the different cameras, but also in some flying birds shots with sky behind the subject, i really doubt if i can see any difference in the speed or accurance of focus between older cameras and the new ones with ai af tech. Maybe ai tech is focused more on marketing than camera capabilities.
So my experience using 6700 for a couple of months was kind of disapointing, but maybe because my special needs of all-intra codec 120p... But the main problem was that evf lacks of good view experience.