Great Choice. I had 2 growing up, and 1 that grew up with my kids. My kids are now grown and the dog had to be put to sleep I could probably write you a book. I had the same concerns as you, and since I was familiar with GSD's we decided to get one. Best move I ever made.
I would however be wary with small kids and big dogs, I think mine were 6 and 8 when we got the dog so they grew up together. Honestly a true working/guard dog and family dog are hard to mix together. ie its not a good idea for an aggressively trained dog to be allowed to lay around with the kids.
My GSD was naturally protective of our family, but it was definitely my sons dog. The dog thought he was one of my kids, but instinctively knew when something was not right and went into full protection mode.
Some issue to consider:
You need to establish who the big dog is, To quote the Dog Whisperer " Calm Assertive Energy"
Great dog if you are able to make him part of the family
They appear and can be intimidating to others, but when properly trained they are really big babies with the family, assuming the pack order has been established
They do get bored and will chew shit up, we probably should have crate trained him for 2 years, before we could let him have the run of the house when we were not home
They are very intelligent, but will test you, kinda like kids do when they are teenagers
They SHED like NOTHING you have ever seen, so be prepared to deal with dog hair forever!
Check into health certifications OFA/DM can be very expensive
Mine liked the cold would lay on the deck in snow and did not want to come in
The poor things tongue hung out all summer[/SIZE]
I was more at ease and felt safer when we had our GSD, than I am now with my alarm system. He was and alarm, guard, and fury kid rolled into one! Never really if the door was locked. We lived in the country and the dog and kids ran through the woods together, just an added piece of mind.
I swear the dog would let anyone in the house if we told him it was OK, but if he didn't know them, I swear he watched them with a DON'T FUCK UP attitude. You would have to see it it believe it.
Me and my wife were sitting on the deck one day, and the dog's ears perked up, then he started wagging his tail and got up and walked off the deck, just then a good friend pulled in the driveway. The dog was excited to see him, but when he got out of the truck the dog started growling... WTF then he spoke to the dog and the dog got excited again, then started growling, then the dog ran back by my wife's side and started growling. Every time my buddy spoke the dogs tail would wag, then he would growl again.. WTF AGAIN!
To make a long story short my buddy was picking berries, and stopped by to bring us some. As ole timers use to do, he wrapped rags soaked in diesel fuel around his legs to keep the chiggers and ticks off him. This confused the hell out of the dog, their primary sense of recognition is smell. After we figured out what was going on, it was truly amazing to see him go from puppy dog to Bad ASS. My wife said Now I know I am safe with the dog when your not around!
Kinda like my kids I wouldn't take 10 million$ for them, but I wouldn't give you a nickel for another one!
Sorry enough rambling, I really don't think you can wrong. I gotta go look at some old pics of the dog and kids.......
I hope this was helpful