I am not against it in principle. If a show-line breeder wanted to inject more drive or better pasterns or some other trait and could not find a suitable candidate within show lines for what he was looking for, he might try a total outcross to a working-line dog.
The selection of the working line dog would need to be made with attention to all the details.
The first generation would probably be all over the place, with very little uniformity. The breeder would have to choose one or more prospects to be bred back into the type that he is striving for (show-lines) and line breed. For this, the breeder would have to let the puppies grow out some before deciding on which dogs to use to breed back in. The second generation might be an improvement in whatever the trait, and in uniformity, but no guaranty. Again, the puppies would need to grow out some before choosing the best dogs, and it would probably be years before it would be evident what besides that trait had entered into his lines.
I think for the most part, many breeders do not have the patience, persistence, or the space to do such a venture right.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC