This will likely sound weird to many of you, but I like playing it the way I do.
NP, lots of people like the sandbox element of the game, and that is easier on lower difficulty level. My usual habit is play for many turns after “the end” even after I win as I like to see if some of the AI are going to have at it. When I loose, I like to be pretty of the tally for how many more turns I needed. And then I discovered that the Dom VC is still available after another VC triggers -- so that can keep me motivated to keep playing too!
That said, your OP, “I don't like having a pop up telling me the AI won a scientific or diplomatic victory, etc. With this off those notifications go away” makes me think you are missing out on some pretty basic elements of the game that the designers put in there for your interest and entertainment.
You are talking about a one-time notification that is dismissed by a single click. And to avoid that minor interruption, you are willing to disable a rather foundational element of the game -- one or more VC.
Jon gives you the bare bones from the XML and a couple of us weigh in that, yes, the AI behavior changes in noticeable and significant ways. Then you conclude by believing what you were hoping to hear, “So far `fairly minor` is proving truer in my case at least” -- even though everyone said the opposite.
I think you are missing out on quite a lot of the available game play. That is fine, it is keeping you entertained, and that is what it is there for. But I think you will enjoy the game the game even more if you play it closer to how the developers expected you to play it -- which is to say, with all the VC enabled, and with you trying to win.
The brain automatically learns by itself even if I take the long way to do it.
Our brains are even better at finding ways to rationalize what we already believe!