Herding dogs when the right one is used can add a lot, in a first x it should bring good coat, feet, stamina, trainability, BRAINS, loyalty. If your looking for a stock dog to breed a first x, look about for a dog that you think 'hey i could hunt that dog' - i.e leggy, tough, good chest, smart, fast, good feet, coat etc and stick it over the best long dog dog bitch you can thats pretty much all running dog and thats your start and then maybe later put a tested bitch pup back to a real good stag stud and there you go.