I have 5 BR's, about 14 weeks old, 1 roo and 4 gals. There have been a few times when One of them have pecked at me. BUT, in all honesty, I don't know that I would call any of those times aggressive. I know that when I am sitting outside on my chair I will occasionally get a peck on the leg. I don't know why, but I could have had a bug there for all I know. I doesn't hurt. My roo will peck my hand if I reach for him too fast. One of the ladies pecked me yesterday, but she was scratching for treats and I have been known to hand feed them treats sometimes. NONE of them will allow me to pick them up off of the ground, but all of them will allow me to pick them up from a roost. They run to me when I call them as if I have been away for a month, but still run away from me like I have cootie's when I walk among them.
They do act aggressive towards my younger chicks when they are out in the brooder pen. Sometimes VERY aggressive. BUT I read about failed flock integration on here all of the time. I think it is all normal behavior. They will get used to them eventually. I wouldn't consider them mean.
I love my BR's. I would have an entire flock of them, 50+ if I had the room, and wasn't into variety.