I use autopilot daily. It drives me, on a twisty road, from my house to work with intervention when I get into town.
> how quickly might it react to a perceived obstacle?
I've had it head towards a curbed median in the middle of the road and within 10 feet swerve to the right to miss it (in a spot that I've driven by hundreds of times, but this time it kinda decided to head towards the curbed median). Auto pilot can react surprisingly quickly in a good way.
So far, for me, it has never swerved quickly towards anything. There are situations, like on blind curves in the mountains, where it doesn't know what to do. At this time, it will start beeping, showing red on the screen and try its best to keep driving: even if that means quickly heading off the road. But, it doesn't act aggressive in any way. This is what I've experienced so far.
I've had auto pilot take me, hands free, between freeway interchanges, merging, changing lanes, etc. and I'm totally amazed. At other times, it does seem to do dumb things and I wonder what it had seen to consider taking the action it took.
Even with all that, there is still a huge advantage to auto pilot. Driving with it on seems to remove >a lotI also have more time to scan the road for anything going on. Looking down to see my speed, for example, (basically any action that takes my focus off the road for a second or two) is less stressful.
It is utterly amazing technology and I still can't believe it is happening while I'm alive.