I just wanted to jump in and say that it is most definitely not impossible to successfully blend the two lines of West German Showlines and Working lines.
Requires quite a bit of knowledge and know how? of course!
I have seen it done very successfully and I admire the dogs and the breeders for doing so.
Sure you are right the pedigree snobs may turn their nose up at the breeding, but when push comes to shove if the dog has the conformation and the working ability then why put a damper on a great dog?
Crossing the lines (genetic diversity) may be the only saving grace this breed has one day.
I do agree that without a great understanding of lines, the dogs, drives, training, breeding in general, that crossing the lines isn't the greatest of ideas.
Just my $0.02
"For the animal shall not be measured by man. In a world older and more complete than ours they move finished and complete, gifted with extensions of the senses we have lost or never attained, living by voices we shall never hear."