Facebook Container is a stricter form of protection for Facebook specifically, so no, you should continue using it if you're interested in isolating Facebook.
Total Cookie Protection is about isolating third party cookies/web storage, without breaking as much of the web as simply blocking third party cookies does.
In which way is Facebook Container "stricter"? Are you aware of any potential third-party tracking vectors that Firefox does not currently mitigate, but Facebook Container does? The only possible difference I can see is that Facebook Container keeps sites "shared" via Facebook inside of the Facebook Container, so if you navigate from e.g. Facebook -> CNN, facebook can only see the history of CNN pages you've visited inside of the Facebook container. Otherwise, clicking on a share link from Facebook (with, e.g., a unique query parameter) would allow Facebook to correlate their CNN.com facebook cookie with their Facebook.com cookie, getting (retroactive) access to all of your CNN history. So maybe that's one reason to continue to use Facebook Container
I'm not sure if it offers any stricter cookie-specific behavior, but it also blocks network requests Facebook makes on third party pages. So unless you're running in ETP strict/custom mode with the content blocker on, or in private browsing, or maybe an ad blocker that also blocks FB in general, that's probably worth noting.
What kind of protection does Facebook Container have other than deleting cookies outside of the container?
For my case Total Cookie Protection is enough, but if you want the same protection of Facebook Container for every website (i.e. session cookies which are deleted each time you restart the browser) you can install Cookie AutoDelete or use the built-in option to delete cookies at restart (whitelisting websites where you need permanent cookies).
It also blocks network requests made by third-party sites to FB. So unless you're already running ETP with the content blocker on (strict mode, private browsing mode) or another ad blocker kind of addon that also blocks FB strictly, then that's an additional measure.
I think Cookie Protection does solve the problem that I used the containers for. I wasn't really using it to keep accounts separate, per se, but more to keep companies like Google from snooping and sneaking peeks at my other cookies.
