This would be helpful so that someone would be able to see who is and is not registered for the event.  This would also be helpful in making a participants mind up on what category they'd like to participate in,  The re is a way to see all who are registered, but I don't believe it is able to drill down & show what category they are in.  Many non-fundraiser events use BikeReg or other programs like theirs and they are able to see who is registered.