I should have elaborated more on the switching of foods. As jan said if you do it slow and over a period of close to two weeks it will not cause an issue. If you are just switching right after you run out of blue buffalo then that will most certainly cause an upset tummy.
I too would not switch if you are seeing good results. Not every food is right for every dog, they are all different and equally picky.
Some high quality foods I approve of.
Orijen
Acana
Wellness ocean core
Precise hollistic
Evo
TOTW
There are many more but these are just the ones I have personally looked in to and agree with the ingredients and manufacturing.
Thanks again.