That question occurred to me, and then I thought it was probably the same value as a women-only sangha, especially if there is a lot of personal sharing because, for some topics, it is easier to share with peers, without having to explain or worry about being judged or offending. I personally never went to any restricted groups but they do seem to have value for people who have more difficulty in making themselves vulnerable or who might want to focus on specific issues, such as the third precept.
