Just finished up disabling the big clunky heap of TreeStyleTabs extensions and other tab addons to give this a shot. I am already deeply impressed and I've barely scratched the surface going through all the config & customization and behavior options all at your figertips in one place with Sidebery. Outstanding work!

*EDIT*
It seems shortly after I posted this review was the last time the github was updated. It's sitting with about 200 issues reported and only a single PR. C'mon, dev people, this is so damn good for FF--it kept me from being forced to a Chromium-based browser for almost a year now. Unfortunately I'm a network admin with no coding languages under my belt, but I just donated with a little note of thanks. It'd be tragic for this extension to fizzle out while it's just picking up more attention finally.