After another 1,000 miles or so on v8 I have the following observations:
The good news:
1) The driving on the 'twisty less traveled' roads is improving. I guess because of the high resolution maps that are generated by my previous drives on the same twisty roads. It is quite some time since I have had the 'veer across the yellow line' problem which occurred quite often when I first started on v8, on twisty roads. So AP does seem to be improving.
2) The AP driving on a trip this week from Atlanta to Nashville and back was really good. No errors on the whole trip.
The bad news:
1) The 'crest of the hill' problem seems just as bad as v7.1. All bets are off what AP is going to do when you crest a hill, so a firm grip on the wheel to make sure AP does not do something silly is required when cresting a hill.
2) There is a use case which is quite dangerous. When you approach stopped traffic directly ahead the radar 'sees' the stopped traffic, identifies the stopped traffic as a target, and brakes sensibly. Every time so far.
However, when the road is curved and the stopped traffic is not directly in front of the car (but is off to the right or the left) then the AP does not acquire the stopped traffic as a target, and does not brake. You had better be prepared to manually brake hard in this circumstance.
I'm sure these use cases are emerging with the additional driving/feedback that Tesla is learning since v8 release, and hopefully will be improved in v8.1.
Overall, due to the better general braking when coming across stopped traffic, v8 is an improvement on v7.1.