We feed 4health to our dogs, they are doing great on it.
We used to feed Purina dog chow, they switched the formula, and it made my older Chihuahua sick.
I have a 8 pound bag of Purina one that was given to me with the newest foster dog (Chihuahua also) she is doing great on it, but I will be switching her to the 4health with the rest of the gang!
Ole Roy was the ONLY food that our Black Labrador could eat with out breaking out in huge scabs all over, it was dandruff looking scabs and he would shed like crazy, even on TOTW. Put him back on Ole Roy and he would heal up and not shed or dig his skin! Odd huh!?
Every dog is different. Some will do good on one brand that others hate and cant eat.
As far as Dobermans go, my friend breeds and shows them, she ONLY feeds her dogs Purina ProPlan performance. Her dogs coats are beyond gorgeous, she mainly has reds, and a few blacks. I wish I had photos of her dogs to show you all. They make peoples jaws drop!