Very sweet, submissive birds. We have 3 Giant Blue Cochins in a pen separate from the rest of the flock (they are younger, bought them for a "giant breed" flock).
Our lowest pullet on the pecking order in the regular flock, an EE, was getting picked on, kept from food, and treated really badly by the other birds. We put her in with the 3 Cochins. One by one they came at her trying for top bird honors, she chased each one away. They only tried once as far as we know. The EE, who is about half their size and REALLY submissive, is head pullet.
I think they would get beat up with our regular flock. Excellent birds, though, laying well, and really quiet (even while laying). They would make excellent hens for an urban setting because of this. They would also be a good choice for families with small children.