I tried it out, but it was much more structured than I'd like. I don't really want to have pre-defined a bunch of containers for each site that I want compartmentalized. I really like the ephemeral nature of private browsing where a single click gives me a fresh new container that I can use for whatever I want. Plus, when giving recommendations to family members, private browsing is more user-facing feature, and easier for them to use.

As an alternative, there is the “containers on the go” add-on, which will let you easily (optionally) open new tabs in ephemeral containers.

When the plugins stop working in FF, multi account containers stop working as well.