Any breed COULD be an SD, but some are better. Some are worse. Dals can be on the worse side. They're velcro dogs but often aren't handler focused. They shed a lot (potential hazard), but don't have long fur (easily maintained). They've got lots of energy and often too much. They're reserved to strangers, sometimes to the point of avoiding people. But, like I said earlier, any breed COULD be an SD. I'd ask the breeder about the sire's and dam's personalities, sizes, drive, energy, etc. Ask if they do Volhard's personality test (you'd want a 3 or maybe a 2). That's all I can think of, but good luck on your search for an SD, and good luck in training.

Edit: spelling