I have a pair of American Buff. They're only 7 months old. I think they're wonderful. No problems with aggression, but they haven't reached breeding age yet either. We see how that goes in the next few months. The gander will go after our dog through the fence, but it has been mostly show. He did hiss at my husband once, but nothing too serious. As for the chickens, if the chickens get too close, both the goose and gander will chase them off, but no major feather pulling, trampling, etc.
They are pretty quiet. They honk if I come outside or if someone drives into the back yard. My parents have said they'll honk if they come into our driveway when we're not home. The gander does most of the honking at that time.
In all, I really enjoy them. They have great personalities and I wish I could have more!