I can speak from the perspective of someone who owned a PPD. Ours was a tri-color/blue merle collie that was being retired from guard duty at an Air Force Base during the Vietnam war. The handler’s son practiced the drums, so the dog kept running away from home during practice time, and ending up at our house. My father had been a dog handler for the Air Force during WWII, one thing led to another,and we ended up with the dog after he was retired from duty. Which was highly unusual, because most often they were retired and immediately shot. He was an incredible dog.
I was 6 years old, he was told to take care of me, and did it 24/7. Walked me to school and walked circles around me in the school yard so no one could get near me until it was time to go in the building. He would wait until he saw me walk up the inside staircase, and then trot home. At 3 pm he was waiting at the corner for me and walked me home. Played with me, slept with me, slept outside of my door if it was closed, or would run down the hallway and headbutt it if it was closed before I went to sleep until someone called him off. No one could ever strike or spank me if I had been naughty, because he would stand square and growl if they moved towards me in a threatening way, then shoot off the floor and grab their arm while growling before they could ever connect with me. Would not let the electric meter reader man on the property because he carried a meter reader, which the dog perceived as a weapon. Would go ballistic at the guy, and chase him off the property. Once the man was off the property, the dog could be called off. Yet he played football with the neighbor kids, went sledding with us (careening down the hill solo while sitting on my sled), frisbee, candlepin bowling, etc. Any sport involving a ball, and the dog could be counted on to join in the fun. When it came to playing with the neighborhood kids in our yard, he was just one of the gang, and never, ever threatened or hurt a child. Best damned dog we ever owned. Dog of a lifetime.
I also worked on a farm property owned by a prominent psychiatrist with a family who owned a PPD GSD–German lines. Another fabulous dog. However, I would counsel anyone working on the farm in the winter to NOT wear a black knit cap. I was cold, knew it could be an issue but put my handmade cap on anyway, and was very glad I was behind an electric fence once I did. Took off the cap, and the dog calmed right back down. Once I came out of the area sans cap, he was back to being his congenial self. I felt safe when he was around. Don’t know the price, but the kids in the family had the same relationship with the dog that I had had with ours as a child.
If you are going to go with a GSD, I would suggest going with one out of German working lines. The conformation is better suited for longevity, and they have not been as intensively inbred as many of the AKC lines have been. I have to say, I boarded at a place with an AKC GSD trained Schutzhund, and while the training was good, it was not up to the level of the PP dogs. Nice dog though, with a good bark, a sound companion on the trails and for a person working alone at the barn, and a good warning system to the uninvited coming to the farm. I think she would have worked okay in a sticky situation, but with a good PPD you don’t have to just think they will work, you know they will. If you’ve got the money to sink into this and want this level of protection, then I would research breeds and trainers very, very carefully, and then make a good choice based on your family’s needs. Then keep working the dog with basic commands on a regular basis. You want them to work well for you when you need them to. That’s what our family did with ours. We didn’t need to do a yearly professional tune-up, but that is a good idea.
ETA: There are military dog adoption groups that adopt out retiring military dogs. You probably won’t get a strictly PP-trained dog, but many are dual purpose trained, and the training is good. Most of them are coming out of war deployments, are high energy and may have a few issues that need to be resolved with peace and quiet for a while at home. They are pricey for the average person looking for a well-trained dog, but cheap in comparison to a well-trained PP dog sold here in the states. If the dog can be flown from overseas into a air base near to your home, that drastically reduces the cost. Don’t know if it is for you, but it might be something for someone to look into. Here is one of the group links: http://www.militaryworkingdogadoptions.com/
There is a telephone number there that you can call to see if there are any near your area that are up for adoption, as well. Lackland AFB in Texas is an adoption center, but there are others across the country, as well. If you decide to go this route with any of these groups, you are looking for a dog that has been trained for Patrol. Additional training is a bonus.