So you would have to go to Germany to get a DD? Or are there breeders in the U.S. that have DD that are registered with Germany?
Can these dogs get titles or complete hunt tests?
Jordan - There are breeders here in the US, http://www.vdd-gna.org/breeders/.
The German testing system does not have titles. It's your dog, you can play whatever games you want to play. That said, DD purist discourage dual registering your DD which you have to do to run Navhda or AKC. Once you buy a DD, you have several tests in which you can participate. VJP and HZP are the breed tests which give you the opportunity to certify your dog for breeding. VGP is a performance test that covers 20+ subjects over two days and produces a finished dog once you complete the test. From there you can do a BTR which is a retrieving reliability test. There is the VSwPO which is a blood tracking event that allows you to choose between a 20hr track or 40hr blood track.
Why a DD over GWP? For me it's the system and tradition. When a person buys a DD, he is buying a pup from parents that have been proven. The parents of that pup have gone through the natural ability tests(VJP/HZP) and passed. Their hips(HD), shoulders(OCD) , elbows(ED), bite, temperament have been tested. They have also gone through a breed show and have had their conformation and coat evaluated. If any flaws are found that don't meet the requirements, the dog can't be certified for breeding.
I am sure there are some great GWP breeders as well as some great GWPs out there. GWP breeders don't have restrictions on the dogs they can or cannot breed. They can breed dogs with bad hips, bad bites, etc.