i have one. they are herding dogs this one chases anything that moves. not recommended for families with small children. very active dogs. i would say other breeds are better suited for guard dogs.
there wonderful family dogs they are gentle, loving and protective with there people,mostly it's natural instinct but you may have to work with him just a little bit,there smart as hell so it wouldn't take long for them to catch on.
Had one a few years ago. They are working dogs, not guard dogs. They would take some training to be a guard dog. Mine was the perfect frisbee catching dog.