Question: Are you seeking an effective community, or an effective stream of new information?

Duplicate information encourages community formation; it makes it easy for new members to join the community, as the average content level never deviates too far from what a new member can readily be expected to pick up. A continual stream of new information very rapidly becomes impossible for a new user to incorporate, and so if the community emphasizes new information, new members have ever-increasing amounts of catching-up to do before they get to participate. Given that participation is part of the appeal of communities, you'll lose the vast majority of all potential members, productive or otherwise. A graduation system doesn't work either; if your best members are always busy discussing the latest-and-greatest piece of information, they're -not- helping newbies past the difficult introductory hurdles.

More simply, you're missing the point of a community. A community doesn't exist to feed you an endless stream of new and interesting things, it exists so you can exchange new and interesting things you've encountered with other people. "Ask not what your forum can do for you, but what you can do for your forum." What you seem to want can be better served by an encyclopedia or textbook.