I'd say dumber because I remember being on Seven and no matter what you used he would never move forward. Turn, back up, spurs, crop nothing. No go. He just stood there. Stubborn, dumb either way all of them seemed to have the same sort of mindset.
I think that's why my Grandpa liked the mustangs better. They had more get up and go, they were willing, they had spunk.
Unless it weighs a ton... it's just a horse. Draft horse motto.