I've had stallions (as in multiple) for over 30 years. Maybe I've just been very very lucky but I've never had problems with them. I currently have just under 40 acres divided roughly in half by a state highway. The stallions, ungelded youngsters and geldings all run in a bachelor herd on one side of the road (there are 9 horses in that group) and the mares and fillies and one stallion (in his own pen next to the mares' pasture) live on the other. I am the boss mare here and all know it....usually a "look" or a pointed finger and a little bit of a "growl" from me is all it takes to change an attitude or stop something. I've had Arab, POA, QH and Paint stallions (the Paints and QH's from cutting/reining/reined cowhorse lines) and haven't found any to be especially "hot" (with one exception...a mishandled pure Polish stallion that was scared to death he was going to get chain whipped ...took a year to get his head sort of straight but he never tried to hurt anyone...just to get away). I've found that for youngsters having some breeding experience actually seems to help their behavior.....they learn that there is one place and time and set of circumstances under which stallion behavior is allowed....and that everywhere else he has to behave....kind of like giving a teen boy permission to "misbehave" at one time/place lets him be more focused and less wild at others....provides an outlet for all that energy.