David,
I am sorry we missed this post...Didn't mean to ignore you.
Err on the side of more space than less. These birds get really big and are very clumsy. If you don't have enough space for them, the poo piles up dreadfully--I mean that in every sense of the word. When crowded they also are more stressed and they tend to step on who ever is in their way--grace and delicacy are not part of the broiler equation. When they step on each other (can you tell I am speaking from experience?) their sharp claws rip the skin of their neighbors back side. When you go to butcher you end up with striped toosh chickens...not a great thing for people who want to sell good looking birds. Also when these white chickens bleed (from getting clawed or otherwise) the blood is really obvious and they get pecked...talk about adding insult to injury.:|
We had to butcher our last two batches at 6 weeks. They were huge. Letting them go beyond about 8 weeks and they get stringy.