To ventilate or not to ventilate?

O.K., dumb question (expect it, I'm from Oklahoma). How many of you carburetted guys use a PCV valve-in non-emmissions states? If so, why? If not, Why not and what do you do with the PCV port on your carb? Do you just use breathers for both valve covers? How does this effect performance and manifold vacuum-both with and without? Remember to talk slow. Thanks.