You specified 4 traits you see as being different, so I'll address those.
Protectiveness. Is there actually anyone out there who thinks a GSD, any GSD regardless of its job, shouldn’t be protective???? If there is, I would certainly suggest that person look to another breed entirely. Certainly in today’s world, this is often considered a bad thing. There was a time when people naturally expected dogs, particularly of breeds like the GSD, to be protective and had no problem with it. Today you might be getting a nasty letter from a lawyer if your dog looks at someone funny, or makes them sneeze or sheds a piece of dog hair on them. Times sure have changed….. And many SD organizations have gone along with the PC idea that people have a right not to be offended or intimidated or scared, no matter how unreasonable, and thus moved away from GSDs lest they scare the public. That is a problem with the world, not the dog. Personally, if I were disabled in any fashion and that might interfere with my ability to spot and respond to a threat to my person, especially if my disability might increase my chances of being a target by making me appear as easy pickin’s to the bad guys, I would want my SD to be able to make up for that. I know many disabled persons who feel the same and will choose the GSD over the Labradoodle specifically for its better deterrent value and protective instinct.
Sharpness. This refers to the trigger threshold for recognizing a threat, and going into defense. Every GSD, regardless of its vocation, should have the ability to recognize a true threat if one presents itself. A “sharp” dog is a dog with a low trigger threshold. While there are some jobs where this might be appropriate, there are not many and I would categorize them as the exceptions that could be considered specialized. Clearly, a seeing eye dog should not be sharp. But then neither should most PPDs. After all, what use is a PPD if you can’t have the dog with you? How is it to protect you if it is stuck in crate or kennel or car lest it be going off on innocent people? More “specialized” PPDs peddled by certain types of (quite often questionable at best) personal protection trainers often do put emphasis on sharpness. But most people wanting a PPD want a dog who can also be a family dog and who can accompany them when they are out and about. If it can't do that, the dog can afford no protection whatsoever. But of course they don't want to be getting sued every week either, so the dog must be sound and stable around people in general and only react if there is a true threat, or if cued to do so (through training) by the owner. A high degree of sharpness is actually undesirable for most PPDs.
Hardness. Hardness merely refers to a dog's resiliency to negative experiences. A hard dog is one who does not shut down, avoid, or have his attitude significantly diminished when he encounters an aversive. Whether as PPD or seeing eye dog, I certainly would not want to trust my safety and well being to a dog who was soft and easily lost focus, purpose and a willingness to keep working, and I can't imagine anyone would.
Defense Drive. Do you understand what defense drive is? Simply, it is a form of reactive aggression that comes into play when the dog's fight/flight response is triggered. The dog with defense drive will fight first, the dog without it will flee and go into avoidance. Different dogs will have different trigger thresholds for perception of a threat (see sharpness above), but once that threshold is reached ANY and EVERY GSD should show strong defense drive in response to the threat, and sustainability of that drive until the threat has gone away. How can anyone say a GSD, regardless of its job, does not need defense drive? That is the same as saying that when a GSD encounters a threat it should turn tail and run. I don't think anyone, anywhere, would say that is an appropriate reaction for a GSD, I don't care what its job is!
