[Building Sakai] Multiple Group Providers and CM impls?

[Maurer, Christopher Wayne]

As I was working on merging SAK-16693 back to sakai trunk (we have it running at IU), it made me wonder about the way I implemented it.
For us, it was fine to replace the default Group Provider with a different one since we aren't using anything out of the Course Management Service.  But, if we were, how would I have done this?
Do other people see the need to have multiple group providers?  Would that only be necessary if you had multiple course management implementations?  

Briefly, what I did was add a new CM implementation that just went back to the site service to get info.  So, a site's providerId is just another siteId.  Then, the new group provider was really just a different set of role mappings in the roleResolvers.

So, what I worry about is, could a school that does use the course management service use this new feature?  I would think that adding my role mappings to the existing group provider could result in "collisions" or at least potentially undesirable role mappings moving through for the wrong CM impl.

I know it might be hard to understand what I described, especially without seeing any src, but does that make sense to anyone?  And are there any suggestions?

Chris