We've had a cockerel with the hens for ages. Not the same one though. Currently it's Hector but there has been Henry (he had 6 wives), Hobbes, Horatio, Hugo and not Hector. None of ours have particularly messed up the hens, current one's not that noisy. They do sort out any battles - we introduced new pullets recently and when one of the "old guard" went to have a go, Hector was right there breaking it up.
I like having a cockerel - he's handsome and looks after his girls, and most have been real characters.