Mac Pro upgrade went swimmingly. Rather amazed that the bash script I wrote to do all the Homebrew installations, dotfile symlinks, zsh setup, and everything else went so well — rare for an untested script to do anything at all.
Now with a 2TB SSD and 64GB RAM I feel quite comfortable even on this 8 year old machine.
Shame I got around to it too late: Team Fortress 2 no longer runs on MacOS.