One thing that gets opera singers (like me) up in a knot about this, is that the human voice is not a tune-able instrument. There are registration issues in fixed frequency ranges, which we can't change. At A440, a register shift happens a quarter tone lower than where Mozart and Verdi expected it. That creates a sound difference that an audience can hear, and a big difference technically.
If memory serves, a number of opera singers, including Pavoratti, were lobbying for a change of the international standard to 432. I thought this was a bit foolish, as the problem is better addressed by simply agreeing to adopt an alternate tuning for those pieces that would benefit from it.
Personally I prefer singing at A=415 since my voice is lower set. :)
This said I think it's more fun to talk about temperaments than absolute pitch, after all unless you have absolute pitch I don't think you can hear much of a difference between something played at 432 or 440, but going from equal temperament to something else is a lot more noticeable and makes a lot more impact to the music if it's written taking that into account.
In addition to varying by era of music, as you mention, this also varies by country. My violin teacher had done a lot of traveling and performing in different countries. She told me that, in one country[0], she was given criticism that her tuning was off in her solos. She realized that they were using A=445, and their ears were trained on that, so everything she played solo sounded flat to them[1]. Once she discovered this, it was an easy "problem" to fix!
[0] I wish I remember which countries - I think Austria and Germany? I can't be sure. I'm almost postive it's not Russia, because I think A=435/438 is more common there - or at least was at the time.
[1] It's only really relevant for solos, because for a trained violinist playing in an orchestra, tuning is done by ear. So a professional violinist would adjust to the tuning used by the group without really thinking about it.
My father plays in a baroque orchestra (the Amsterdam Baroque Orchestra), and I know that when they play a repertory, e.g. Dieterich Buxtehude, the orchestra tunes to 465 meantone.
The regional variations depends a lot on orchestra politics. For example, when I played the munich phil in the late 90s they started at 443, but concert heat be damned, if the last chord wasn't 443 there were some yelling at the first violins and brass section for striving to much upwards.
The Swedish radio decided to play 441 for political reasons (it was a compromise that stuck), and I think still does.
I can say as someone who performs a lot of Baroque music (c. 1600 - 1750) that there is a relatively common standard of A=415 for music of this period. A=415 is often referred to as "Baroque pitch."
This mainly applies to ensembles that specialize in Baroque music, and use historical instruments. If you see your local symphony orchestra play Bach on modern instruments, they will probably play at A=440.
I have never performed at a pitch higher than 440. I'm sure it happens sometimes, but I think it's more of a niche thing.