Fantastic addition that should probably be built into Xenforo. Allows me to let mods manage access to selective groups, to regulate private areas of our forum. (without having admin access, and creating a potential security problem)
This is an excellent addon that I strongly recommend to every forum. From easily accessible tailored ban/restrictive permission options for your mods to use on problem posters to user directed social groups, to easier testing & quality assurance; this addon simply makes life easier.
Seriously, download it and I strongly doubt you will have cause to regret the decision.