We just had an example of differences between the same breed with a German shorthair dog that was the most stubborn dog I have ever had. He was very timid of people as a puppy but had gotten over that with training. I paid a professional trainer as I couldn't get the here command down along with other issues. I had a lot of things going on in my life that happened right after we got him so I couldn't put the time into him that I needed to. The trainer help tremendously but the dog would still occasionally when chasing something run through the e-collar turned max yelping and holding his head sideways through the pain. He had gotten much better for me but my wife still struggled with him. She had him on an exercise run near dusk on a farm field and he got on something and wouldn't listen to her despite having the collar ran up to the max. He crossed a road and got hit and killed. It was traumatic for my wife but sadly a reminder of being firm and consistent from the get go. Part of the problem was he reached a year or so before being introduced to the e-collar and let run without repercussion when we went on a run just to get rid of the energy.
We just got another one despite my wife's fear of it being a "German Shorthair thing". The new dog is almost a year old but won't runoff when you aren't looking and listens for the most part. Still some training to go but he is manageable. My wife is relieved and so am I. I am starting the e-collar now as the previous owner didn't but the dog is certainly way more laid back than the previous GSP.
Another breed for you to consider since you are looking at smaller dogs would be a Vizsla. Almost like a smaller Weimaraner.
