The Gentlemen roosters are usually the least dominant ones, in my experience. They usually get beat up by their brothers on a regular basis while growing up, and can even get a good talkin to by hens.
The key turning point is as the others stated: around the one year mark when testosterone is floating their little brains away. Just hang in there, and observe them closely after they clear their maturity hurdle. It's adorable when you get a gentleman roo, because they'll gently tug on their ladies' wing feathers in question when they want to mate ("excuse me, if it wouldn't be too much trouble...") and do pretty dances. They'll mount and balance without feather-pulling, or spurring their hens. And they'll point out tasty treats, and let the hens eat first when they find something yummy... without lying (yes roosters can lie to get hens close for mating, though the hens catch on after a while).
As an interesting point, I recently got ahold of a book that has in-depth studies into flock behavior. In it, several studies were cited where 'experienced' hens prefer these roos as well! 'Inexperienced' hens liked the loud brash fight-winners, but after a few rounds of rough treatment, distinctly changed their preferences to gentleman roos, even if they were the losers of a fight between roos. The book's name is The Complete chicken. A good read!
Too many people put up with aggressive roos that are nasty to the hens. Not allowable in my house. I feel it's part of my role as a steward of animals to ensure they breed in a constructive direction. I don't necessarily want a cuddly rooster, but one that treats my ladies well. That's his most important function.
