Ok, so it is a great guard dog in your eyes.....
Can you turn it on, and turn it off??
Just because a dog jumps at the door, and puts on a good show, does not mean it will perform when the threat is real. Indeed most will break, and run, it is natural.
I don't think you guys see the whole picture. this dog has been likely reinforced to be dramatic, and in doing so loses the calmness needed to make good decisions based on sound training. This is why she bit the owner when she got excited. It is a symptom of a problem, that can create a liability
Great, she will eat up an intruder, not so bad, but if she eats up an excited screaming child, or overly playful hollering adult, then you have a problem.
This is not a bad dog, or dangerous, but it is untrained, and can be dangerous.
My argument is to teach the dog acceptable parameters for turning on, and turning off the behavior, so as to make it more stable.
Owners who expect their dogs to protect them can be very disappointed when it comes time to perform rather than make a show.
The dog has the potential, but not the training.
That makes him a liability, and a loose cannon.
We all want our dogs to protect us, but going crazy at the door is not a signal that the dog will do such, it is a sign of fear, and a measure of instability, or lack of confidence. Little dogs go crazy at the door, and most will be under the bed at the first harsh word, expect no different from a bigger dog
Be afraid of the dog that sits there waiting, and only issues a couple of barks, or a low growl. That dog does not need to put on a show, he knows he is tough.
The guard drive is a good thing if used properly, but one wrong bite and somebody else will be living in your house, driving your cars, because they sued you, and took it from you.
So I still stay find out more about guard, protection defensive, attack training etc... and train accordingly.