It is little talked about and perhaps little used. It has its place but it has one little caveat that can render it a problem.
I am using the transition out MPR to fire off a workflow. The problem is when the MIM user is deleted, the Transition out MPR is also triggered!! It is baffling because one would think how can a object that does not exist still “transition out”. Well I guess technically transition-out means “no longer a member” of this set. I had to chuckle because there is my workflow searching for this user that is no longer a member of this set and it sends an error saying “I can’t find the user!!”