I think its because they are receptive, responsive and historically have proved their ability in various situations (Working lines, not bench warmers).
Bosun, some good points raised, I don't know if I will train another protection dog for my home, perhaps one that just lets me know if anyone is about will suffice? Who knows.............
The trouble with manwork is it attracts the macho men who want a 'ard dog to make them feel tougher. I have never taught manwork unless I feel the dogs temperament was sound and a good foundation level of obedience had been installed. We had one 4