I too am interested in a sustainable flock. I accidentally bought a jersey giant, thinking I was buying an australorp. I ultimately had to kill the rooster because he was so rough on my hens. the thing is, his problem was directly related to his size, not his temperament. if he'd had girls big enough to handle him, he would have been a great rooster. he was a year old & weighed about 12 pounds. I didn't dress him out, so I don't know what he was dressed weight - but he had a lot of meat on him.
he was very protective (fought off a hawk), but never human aggressive. he wasn't friendly. in fact, he was down right suspicious of me - but not once did he offer aggression. he was hard on the girls only because of his size. he foraged very well and put a lot of his weight in his breast. I've got two chicks of his that i'm going to be very interested in how they turn out.
i'm going to give jersey giants more thought.