I love this addon and have been using it for years. It's very useful for a kleptomaniac power user like me who keeps hundreds of tabs and needs a way to sort them. STG has its own backup function as well, which has saved me a few times when Firefox bugs and fails to retain its state. I also get the impression STG helps avoid Firefox getting overwhelmed and degrading performance.

My only issue is that it currently has no compatibility with the new native Firefox tab group function, which prevents STG backups from saving Firefox groups. Hoping that comes in a future update!