I Love Rotties. Your guy looks like a real champ.
I can relate on the guard do story...My oldest dog ,who is 16, used to be a great gaurd dog. Just a couple mounths ago a religous freak came to the door preaching to me (Ugh I hate when they do that, I mean if you believe it than okay, but no need tp push). Any way Red, burst up at him like he had a rocket in his bottom, barking like a psycho, and ole' Blue just slept through the whole comotion.