I think alot of it has to do with how each individual conditions their dogs too. If someone isn't conditioning a dog the way it needs to be, the dog is never going to perform to it's fullest potential. That same dog could be in someone elses hands and be an amazing performer. This goes for any breed of dog. I've seen this scenario with my own eyes. I've also seen dogs that just flat out don't work well for one individual, but will work GREAT for someone else.
I agree, our dogos have to have a lot of exercise. We have a spring pole and we run them.