I am all for breeding a rooster that is not aggressive. I have been doing my own little experiment with my Araucanas. And I fully agree with those of you who think removing aggressive hens from the flock is one step of the equation. Three years ago I was breeding my Araucana rooster (who I have owned now for 5 years) to a flock of Cuckoo Marans hens. I had a market for the resulting cockerels at the age of 6-8 months of age. I was finding that by 6 months of age some of them were getting aggressive to me. So, the next season I put the 2 hens that were making the flock miserable in a seperate breeding pen, marked their eggs, marked the cockerels when they hatched and raised them out. Sure enough, the cockerels that were hatched from those hens were the nasty ones. So, I no longer keep aggressive hens. I consider it a lesson learned! I personally don't think it takes many generations to reach the goal we will be striving for.