I personally consider the right rooster to be an excellent addition to a flock. Bad roosters can be a huge detriment, but if your boy is being good to the hens as well as you, I say keep him. Roosters will warn hens of hawks, their large size can intimidate some of the smaller predators, and I personally love the sound of rooster's crowing and cackling. You also have the ability to hatch your own chicks.
Mating always looks a bit violent. However, if most of the time they are squatting for him or easily submitting to him, then they're doing just fine. If he is chasing them a lot (occasional chasing is normal), then he ought to go, but otherwise, he sounds like a great bird. Also, chickens specifically developed a "clocal kiss" rather than more invasive forms of breeding to minimize all injury and damage to hens. Occasionally you get a bit of feather loss from young or clumsy roosters, but this is easily solved by hen saddles if it occurs (which, in addition to protecting hen's feathers, are available in many stylish and pretty patterns!)