It is very possible that can can be dangerous during that time, and at all other times he shouldn't be taken for granted. Horses, for that matter, definitely can be dangerous. I have a wonderful APHA Stallion who is VERY un-stallion acting. His manners are A+ and he is very willing, submissive and obedient to me, but I never turn my back on him simply because he is a stallion and the possibility is always there.

Are you planning to have your Fillies bred? All three are of breeding age actually.