I don't have time to read all of these replies here, so I hope I'm not repeating anyone, nor going against anyone's opinions, I'm just writing about my own experiences and knowledge on the stallions and what I believe to be true. ...
I find that when a stallion is treated right away as a possible problem child, he turns into one. I believe that many people just assume that the stallion will become difficult, harder to control, and in such belief, tend to train him with that underlying tone that tells him he is different from the other horses. (Which he is, but this tends to make people single him out.) I have seen barns in which the stallion is usually kept at the far end of the barn in a darker stall than others, he is not allowed the same turn outs as the others, and he is almost treated as if he's a wild animal instead of the beautiful companion he could be. I totally believe that if a stallion is treated under such beliefs, then that is exactly what he will become.
Regardless of the urges to breed, dominate, and fight other stallions, he should still be treated as the other horses in his barn....do we think he doesn't notice the difference?? If a stallion is treated in a respectful manner, (with you knowing full well that he needs a firmer hand, more understanding, and possibly more patince)...if he is given the same rights and freedoms as the other horses in the barn AND it is understood that he is just as much a social animal as a gelding and needs to "feel like a horse", then I beleive a stallion can grow into a very respectful gentleman.
I am not saying that such beliefs go without due respect, an ill handled and ill trained stallion can surely become a dangerous animal, but so will one who believes his life is treated unfairly.
I just find it to be of no surprise when I walk into a barn and the owner says "stay away from the stallion in the back.." Well, perhaps what he needs is less people ignoring him, and more people to have approached him in his life and a lot more of a chance to socialize, and not have a stall in the back somewhere.
That is my opinion on raising stallions in a nut shell....I could go on, but I think you get what I mean.