Since this is a Dobermann forum, perhaps a less emotionally charged way of examining the issue would be to discuss the differences in another breed.
Take the German Shepherd Dog as an example. With very, very few (statistically irrelevant) exceptions, GSD's in police work are “European” dogs. Meaning, that even if they were bred here in America, they come from pedigrees or breeding programs that use European style temperament testing.
It's not just about bitework either. There are plenty of single purpose detector dogs. Some of those dogs don't have what it takes to do Patrol, others were simply acquired as single purpose dogs and never trained in patrol. But again, the dogs that do not come from pedigrees and breeding programs that included European style temperament testing are so few as to be statistically irrelevant. This isn't some sort of anti-American prejudice. It's just a fact that you seldom find dogs with a work ethic coming from breeders who don't temperament test their breeding stock
Bottom line is that if you want to have the best odds for reproducing athleticism, nosework, confidence, stability, “Drive” and so forth, you MUST test for it in your breeding program. Then you must breed the dogs that actually pass on their traits and eliminate from your breeding program the dogs who don't pass on their traits. The most successful breeders seem to almost have a magical ability to match up dogs, but the only way to verify the results is to test, test, test.
It's not about what country (or continent) a dog comes from. It's not about 'show' or 'work'. It's not about how the dog looks. It's not even about where the dogs in the pedigree come from. What it is about is breeders making an effort to reproduce a certain temperament.
The only way to to evaluate your breeding stock is through honest testing. The work ethic can be secondary to looks, or it can be primary to looks, but when temperament testing is a key part of the breeding program the resulting dogs will be different from those where temperament isn't tested.
In the German Shepherd Dog world, there is a vast work ethic difference between dogs from tested pedigrees (“European”) and untested pedigrees (“American”). That work ethic difference extends far beyond just “bitework”.