Great add-in, should be built-in! Just one thing missing: it would be great to have a manager showing which site is assigned to which tab group, with the possibility of editing and adding new sites.
Background:
I have an issue with MS Sharepoint links opened from MS Outlook, they open in one tab group (none), are then redirected to another one ('work') for the microsoft login, and finally I end up with the landing page of sharepoint, rather than the document I wanted to open; some info seems to get lost on the way. I think the browser skims over some redirected site which is not in the right container on the way.