I am attaching a link for you to read. As with all things, the German people are really good at making the best better. The DDR dogs are no exception. The independence, hardness, aggression and athletic ability are no accident. To put it bluntly you are asking for a dog that will scale your six foot fence faster then you can say no.
Sequoyah German Sheperds - German Shepherd breeder in Soddy Daisy, TN (sequoyahshepherds.com)

 

My current GSD is DDR. Before getting a DDR, I sought advice from Cliffson1 on here and told him what I wanted to do with the dog, I explained that I wanted a companion and wanted to do tracking and PP, he told me that a DDR would be suitable for what I wanted. Let me tell you, she is very independent and dare I say obnoxious😂 very aloof with strangers, even to family members, she sticks to me like glue. She loathes other dogs, except for my Lhasa X. She knows obedience commands but can be very head strong and if she wants to do something else she will, I spoke to an old trainer and he told me that in his experience, you have to keep enforcing the commands because they seem to have the opinion that they know best, I used to do obedience competitions when I was younger with my previous GSD's, so I know she is being given the command correctly. I was upstairs one day, and I heard here running upstairs, so I shouted down, for her to go downstairs but when I looked, she was literally in the down position on the stairs facing down, she would have stayed in that posistion for as long as she could. Then there are days when words fall on deaf ears.

She has little to no prey drive, her defense drive only kicked in when she was 10mths and it is very high, she is almost 4 years of age and for the last 2 years her hunt and play drives have kicked in, she is not food motivated at all. There are times when I do need to be firm with her but other than that, she is exactly what I was told she would be, and I would not trade her for anything or go back in time and choose a different type.