I just want to say that the theory of only breeding dogs who are great to other great dogs is the only way to get great offspring is not true in my opinion. A dog has genetics just as people do and those genetics are what will make your dogs. For instance if you have two littermates and one of them is average and one is really good, in my opinion their offspring will have the same genetic make up and therefore be the same dogs. Something else to consider when calling a dog or dogs great, are the oppurtunities they have to learn their craft.
you make two great points, however breeding greatness to greatness should be a breeders montra!