I have a 15 hand haffie - we do 15 mile competitive trail rides, and he has no issue carrying the ~300lbs of me + tack that distance. He is happy to work, but really *needs* to be worked in order to be happy - otherwise he gets bored and causes trouble (dumps water troughs, breaks through fences, bosses other horses around, etc.). I know some people view the fact that they won't just do what you tell them blindly as a negative, but I love love love that about my gelding. I always feel like we are partners going out to explore the trails together rather than that I am having a glorified pony ride. He likes being out, he goes out with ears forward, looking at the world and though he finally has gotten to the point where he defers to my judgment when we come across things that he is very unsure of, he still thinks about them each time we come across them before turning the decision over to me. They are thinkers for sure, but as everyone else has said, you cannot let them get away with anything, because if you do they will keep pulling it for the next 10 -15 times that they are asked to do the same thing and it gets to be a pain - they will constantly test to see what they can get away with.