I never really got to grips with having different sets of tabs within the same window -- that's the kind of thing I use multiple windows for. But I still have the extension installed because it's the easiest way to show several hundred tabs in a way which means I can avoid loading the content just to close tabs.
There have been so many forks of this, and they have all been buggy or gotten stalled. This one in particular randomly forgets some of your tab groups. ("you had ONE job!")
I never really got to grips with having different sets of tabs within the same window -- that's the kind of thing I use multiple windows for. But I still have the extension installed because it's the easiest way to show several hundred tabs in a way which means I can avoid loading the content just to close tabs.