Not all classes promote by age or grade. The following feature would help automate promotion for different types of classes or groups.
As a user, I can define a promotion path for a roster or class - to assign participants to the next class (for example, once participants have completed a 101 class, automatically assign to the roster for the 201 class.)
The method I am looking for is the ability to map rosters during promotion. We split out our middle and high school kids into boy and girl groups. I have an idea for a work around but not sure it will pass the "this is just too complicated" test. I think mapping is along the same lines as Elliott's request but still using Grades. I do see a need for random, automated, promotions.