I think you found your answeres here, or at least hopefully. Every dog is different, I've had many in my life and some are just fine on the cheap, red dyed dog food that showed evidence in the backyard of how much was NOT absorbed into thier systems, and now I have a Springer who can't handle much meat. So she's on a vegetarian dry kibble based with Avacados and I give her home cooked meat and the occasional cooked egg ( since I have plenty ) for her protiens. Thus, smaller poo!
So what ever your wallet can handle and as long as it's feeding your dog it's nutritional needs, your all set. There are so many options out there and good food is not all expensive. A lot of the time, the healthier foods require less in serving size too.