Sam knows our dogs. Sam has accepted guest working dogs when we are present. Sam took offence in one case where the guest working dog was "out of control" and harassing the sheep; in that case he started going after this dog. We have "regular" guest working dogs that Sam accepts when we are not present. He can be a bit of a pest when we are training in that he may go lay in the middle of where we are training; typically we lock him up when we are training. We don’t lock him up when we are simply moving the sheep.
We have seen Sam stand between a stray dog and the sheep; barking at the dog. We have seen Sam stay between the sheep and Ag personel and other workers when they are on the fields. Regular guests he recognizes and accepts.
Great Pyrennes are supposed to be the most people friendly (but have the longest coat).
Maremmas are not quite a people friendly and have less coat.
Akbash & Anatolians are supposed to be less people friendly and have short coats.