That's interesting. I want a GSD because they are big, beautiful, loyal dogs, but additionally, I have always thought - as most people do - one would be great at protection/defense.
What kinds would you suggest more strongly?
:typingfail:
GSD's can excel at both. With many breeds it comes down to training. My point was that they focus on the prey drive of these breeds, and never develop their defense. They train as if training for LEO or sport work, which is typically 'apprehension', and depends heavily on prey behavior for training purposes.... chase down and hold. One of the things the sport world emphasizes is a prey-type bite. They teach the dog to bite, deep and all the way to the back of the mouth, and hang on, even if it means dangling in the air. This is a sport derived style, initiating with Schutzhund, and was popularized as the 'proper' way for a dog to bite when the training was marketed to Law Enforcement in the 60s and 70s. Schutzhund, however, was never intended for practical exercise. It was to show the trainability of the GSD, not to be used as an indicator of practical purpose or working efficiency.
A protection dog should fight, not just bite, and the training needs to put the dog on the defensive, where the bad guy is an actual threat to be defeated, not simply a prey object to be held. Prey drive is satisfied when the object or target is in the mouth. Defense dictates the object either be destroyed as a threat or leaves the area. GSD's typically do not suffer from this, but many other breeds not bred for defense drive will flee rather than fight when faced with a real, aggressive, threat display.
A protection dog's job is not to run down someone who is running away. It is to counter an incoming threat, and either destroy it, or tie it up long enough that you can get the fam safely away. This means the dog may have to enter into a protracted battle with the most dangerous of all predators, man. If the dog is trained to bite and hang, he's going to be in for a shock when the cranked up bad dude starts wailing on him and attacking as if the dog is the prey object.
I've seen IPO III and LEO dogs blow their anal glands in fear when treated like the prey. The dog needs to be conditioned to face an entirely different circumstance than sport and LEO dogs are trained for.
When I meantioned breed, that was because typically, but not always, certain breeds tend to be more defensive while others are higher in prey. Rotties tend to be defensive... they may be 'herders' to some people, but that is a misnomer. Being used for Cattle, they have to be defensive. Facing down a Bull or protecting a cow from something big enough to predate on it, is a wee different from the same with sheep....
Boerbels, Presas, Dobes, AB's, etc tend to have more defensive traits. When a prey driven dog bites, it bites and hangs on. In defense drive, a dog will fight rather than simply bite... the hit over and over, move around the body, and cause as much damage as they can. Picture the difference between having a dog latch onto an arm or leg and just clamp down, biting and hanging on to one location, and a dog that hits an arm, kill shakes, tears it's teeth through the skin, hits a leg, hits the other arm, etc ripping flesh and muscle with inch long canines... Which one is more likely to bring the bastiche down?
Just like there is a difference between how a cop fights to restrain a perp and how a Soldier fights to destroy the baddy, there are different ways of fighting for dogs as well, depending upon the goal.
Forget the fact that if you send a dog on someone who is running away you are in big trouble.
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And the other day the pizza guy knocked ont he door...he followed me down the steps and I thought he was getting the idea..but he just wanted a piece of pizza 
he is still a baby just yet, and has just recently started to be alert when he hears noises outside..so I'm hoping it's coming. Hes just too damn friendly and sweet. good for nothing mongrol.