For those of us who are lucky enough to own a 1D-X or a 5D-III, one has to ask what took Kelby so long to see the benefits in features and image quality these cameras have over what he has previously been shooting.
Sure, Kelby is entertaining and his books are helpful at times as reference materials. Do I care what cameras he shoots? About as much as he cares about what cameras I shoot.
I've been to a number of his courses and he doesn't seem to be much of a "shill". Yes, his businesses are closely aligned with Adobe, but teaching Adobe products is what he does and why people attend. I've been a NAPP & Kelby Training member forever and have many of his books. None of his products advocate one camera system over another.