I just wanted to say that I think it really depends on your pig. For anyone who wants to try it, I'd definitely do some careful monitoring and daily head counts of your flock. I have a potbelly pig, and he grew up with a goose and chickens, including an undersized hen with a severe limp who likes to follow/sleep with him. He free-ranges right along with the chickens, and they absolutely love him. They like to follow him around when he's rooting, and pick out bugs. He's never tried to eat them, but I have seen him bite the goose and shove the hens when they go after his food (for some reason, he NEVER even snaps at the hens, only the goose).
I was also holding the goose behind the head one day, because she's evil and bites everyone, when the pig came up to me, and I saw him think about eating the goose (sort of approached the goose's neck all open-mouthed), and then rethink his decision before actually chomping down. I swear, I could see him calculating the cost/benefit!