I linebreed all the time and they are not clones, they vary a great deal. They may look the same at 8 weeks but they are different dogs at one year.

They all vary to a degree, yes.

But I've seen littermates (even half siblings) trained by completely different people who don't know each other and you can still see certain traits that are similar.

You don't know exactly what you'll get but you do know to a degree what to expect from a litter.

Also, no one said buying a Schutzhund dog means buying a protection dog. That's your weird misinterpretation. I agree with that.

You're saying that NO schutzhund dogs cannot work in real life, and that's simply untrue.

Working
Show

Your chances of a natural protection dog would more likely come from working line.

Your chances of getting a good K9 for the street would be from the working lines.

Your chances of a good sport dog would more likely come from working line.

Your chances of getting more then just a show dog is luck from the show lines. Quite possible a good pet also.

Any of these lines could throw something that can be excellent at all three but it wouldn't be the norm for any of them.

I've personally seen show lines in both the World and the National Schutzhund trials and the performance didn't compare to the working/sport lines.

I've personally watched the GSDCA WUSV National show and the show line protection routines were laughable. Their SCH titles are a joke!

As to looks, I've seen more working line dogs that appeal to me visually then most anything in the show line. I've seen butt ugly in both lines. I will go so far as to say that the German show lines are light yrs ahead of the American show lines in both looks and temperament.
There are always exceptions to what I've said above but if I were to select a dog for working or sport my odds would be much higher in the working bred lines.
If I would be looking for a show line dog my odds would be in a show line dog.
If I was looking for a pet it would be from the working bred lines first.

(answering original question)

I'd argue that the difference between the two (formal genetic analysis and use of the dog aside) is that showline dogs are selectively bred for looks, while working dogs are selectively bred for temperment, drive, structural soundness, etc.

If we look at the "selected traits" for each of these the showline dog is all physical things you can see on the outside and has been selectively bred that way for decades. It just has to be just sane enough to not go nuts while being trotted around a ring which leaves a lot of room for traits that are less desirably nut not as visible to get in there. This is why you'll see more temperment and drive issues in a showline dog. That being said that doesn't make showline dog "bad" , there are many breeders who do not settle for "just passing" (winning in conformation) to evaluate a breeding animal. At the same time there are breeders who don't even make sure their showline dogs can win a show....however if you're looking for more than physical traits then perhaps look at working line dogs.

A working line animal is selectively bred to do specific (or general as the case may be) work. This will vary depending on breed (for example, the lab who kicks butt in schutzhund=prooooobably not the animal you want being bred for the soft mouth retreive of the lab) but physical soundness AND stable temperment are generally universal. I would argue drive depends on the breed. This multiple trait selective breeding (and more vigorous testing when it is done) for decades (or centuries) gives you a better chance at getting a dog who's got those elements than selecting from a showline dog who has not been selectively bred for generations to have them. If I had to roll the dice on a BYB dog...I think I'd still go with the working line in many cases....

Mr. Finley;

What is your opinion of the WUSV's emphasis on extreme angulation in its breed standard, which was adopted by the AKC and is one of the main criteria in judging conformation in GSDs?

Do you feel that the degree of angulation has an effect on the length of time that a GSD can stay engaged in extreme physical activity?

My choice for basketball players would come from black men. My choice for accountants would come from white men. My choice for Soccer players would come from English men. My choice for ping pong players would come from Chinese men. My choice for chess players would come from Russian men. My choice for Hebrew readers would come from Jewish men. My choice for marathon runners would come from African men. Working line is no different than a racial stereotype.

 Quote: Charles Finley

My choice for basketball players would come from black men. My choice for accountants would come from white men. My choice for Soccer players would come from English men. My choice for ping pong players would come from Chinese men. My choice for chess players would come from Russian men. My choice for Hebrew readers would come from Jewish men. My choice for marathon runners would come from African men. Working line is no different than a racial stereotype.

Well, this thread just took an interesting twist.

OK, since I'm definitely out of my element in this discussion, I'll go back into the stands now and continue watching this interesting show.

Carry on.

My choice for GSD's? Anyone but Finley. My choice for training advice? Anyone but Finley. My choice for nutrition advice? Anyone but Finley? My choice for replying? From now on, anyone but Finley.

 Quote: steve strom

My choice for GSD's? Anyone but Finley. My choice for training advice? Anyone but Finley. My choice for nutrition advice? Anyone but Finley? My choice for replying? From now on, anyone but Finley.