I have a wishlist member plugin license that I am planning on using on a wpmu site. When I contacted wishlist asking if that plugin was compatible, they had told me that it wasn’t tested but they thought it would work just fine.
I can give you more concrete feedback in a week or so.
Other than this, unless you are interested in restricting BP-specific pages to different membership levels, you are really looking for a wpmu solution. This wpmu-dev plugin claims to do that.
I don’t see why this should be out-of-date. It is obvious that there is an interest in this type of functionality. What is wrong for a thread to go over for months -if (since) it still generates interest?