I've always used FF and Chrome, flipping back and forth as Chrome filled in where FF had issues and vice versa, but after a week or 2 on Quantum I just didn't need Chrome anymore and uninstalled it. Haven't regretted it once.
(also, I'm 90% FF now too)
Hopefully that'll be fixed soon...
Currently the global history is shared between all containers.
[1] https://github.com/mozilla/multi-account-containers/issues/8...
You could look at it as silly, but in those 6 months it saved around 700 work hours after it had paid for its dev time.
Each container can load any page. If you want to toggle the current domain to load in the current container, you can opt for that. Then, it will prompt you to switch to that container when you browse to that domain, and at that point you can opt to make it automatic. If you don't make it completely automatic, you can just choose to use the default container for that domain, or stick with the current container (or source container, if opening a new tab from some other container).
What would make this better would be to be able to flag a domain as openable in multiple containers, but have one be default, so I wouldn't have to decline switching to my personal Google container every time I clicked a link on an email in one of the G Suite accounts, as they redirect to a google landing page).