I have always noticed there seems to be a big variations in how different gsds look when they are in a stack position. They seem to range from a dog that looks like it's just standing there normally all the way to some that you expect to end up in the splits. Is there something that says what a correct stack is supposed to be or is it just judges preference? Are there any good books that you guys recommend that cover the conformation showing stuff really well?
The dogs rear is going to pretty much dictate the stack.
As for handler attire, those AKC handlers would be coming out of the jackets and ties after about the third lap at full speed in a german show ring.