Pros: Proactively strengthening each breed
Cons: No ability to order or pay online
I've been a fan of Glenn Drowns at Sandhill Preservation for some years. He is in the "business" for the purpose of preserving, and improving, a large number of rare (and not so rare) breeds and varieties. You can be sure you are getting genetically pure birds. I've always had great luck with their chicks being healthy at delivery.