Temperment with roosters seems to be part nature, part nurture. Sure, there are tendencies among breeds for behaviors, but you'll find as many different opinions & personal stories as there are members on BYC. For every breed that is "supposed" to be ___ you'll find someone with a testimony about their roo that was the opposite. I've had giant roosters that were gentle and tiny bantams that were terrorists.
This I can say for certain: There really ARE docile roosters. And there are many many many more roosters in the world than there are "job openings" for them away from the table. Therefore, there is NO reason to have to put up with any aggressive behavior from any rooster. Just send them Across The Road and audition your next roo.
With your mix of breeds you could try any type of rooster, even a mixed-breed. They are often more colorful and interesting anyway. Check your local Craigslist, feed store bulletin boards, even other local BYC members. You should be able to find a nice roo for free or little cost.