Great addon for saving tabs for later.
Also, using bookmarks as a session storage is a good decision.
You can use any bookmark addon to work with sessions for e.g. syncing between different computers and so on.

Unfortunately "Crash recovery" does not working as expected.
After I close and open browser most of my tabs in last session (from "crash recovery") is lost because URLs contains some garbage (tab title or something). It happens to me in 50% situations.
FF 56.0.2.