Forget the breed, the horse has to have the 'want to', first of all.
Secondly, some Appy's are nothing but QH with spots (i hate that kind) but in that case, they're just as good as plain old QH.
My appaloosa is pure appaloosa. He has stamina, agility, endurance, and he is extremely smart. He is 2 1/2 and knows how to neck rein already with the first two times I rode him to teach him, he had it down. Of course since he is so young, I won't do anything major until his joints develop more if not completely. He is 14.3 hh. My boarder says he will make an excellent barrel racer/ pole bender/ whatever I want to do with him! Of course I never plan on going Pro, just to local rodeos, and hopefully on the college team =]
Lettin' the cat outta the bag is a whole lot easier than puttin' it back. -- Unkown