I love the idea, but I wonder how feasible it is to implement such a system, with regard to server resources and bandwidth concerns. Also, they would have to classify just about every action, item, location, etc. in the game as belonging to certain knowledge areas/leads, which surely adds to the database size and query times.
Constant checks/dice rolls for leads in just about every aspect of the game would have to push a lot more information per player character over the network, I would think. With hundreds or thousands of players constantly roaming around having checks made all the time, that's a lot more network packets moving around, eating up bandwidth.
Again, I love the idea, but it may have to be put on a back burner until such time that all of the technical aspects could be worked out and guaranteed that it won't negatively impact the performance of the game.