As an epilogue to this thread, I wrote a role compression handler similar to the one I described earlier in the thread.  I haven't fully tested it (and it may be partially uncompleted -- I don't recall offhand).  It got lost in the shuffle of more important projects, and I failed to even mention here that I had made progress on it.  I recall getting somewhere on the order of 500-750 roles per user.

While it's possible that there are issues with it (and it may be only partially completed), I'm happy to take a look at wrapping it up if there is still interest.

@Hollywood: I would not recommend rewriting the MembershipModule; as a design rule we generally discourage any modifications to the core code.  You can accomplish similar functionality, however, by creating your own HttpModule and executing it prior to the MembershipModule in the pipeline.  This would achieve the results you desire without any core code change (and in a much more straightforward manner).

Brandon

DNN is so great at so many things that I'm surprised something so banal as 'a user in more than 40 groups' is an issue.  

It seems many of the responses in this thread center around the idea that Roles are being used incorrectly because we as developers were not aware of an esoteric shortcoming of the Role system. True, many sites will never come up against this limit.  The small sites I build for photographers will not.  The big social networks I build for large clients are.  Right now.  This issue is especially insidious because it doesn't pop up until your site has been live and in active use for a while.  By that time, rewriting a bunch of code to accommodate a unexpected shortcoming is an expensive option.

• Do not use Roles to manage group membership, only use them for general page/module security.
• Keep Role names as short as possible.

Dave