Okay, so I started this thread because when I ordered the brown broilers, I just couldn't find any info on them. So after I raised them and butchered them, I figured I would put some info out for everyone else.
Here's the scoop. They do grow slow, I killed most of mine at 12 weeks. Only the roos were really big enough for broilers. The hens were fryers. (this differs from the cornish rock crosses [I will call them "crosses" from now on.]) They are a clean chicken because they walk around (this too, differs from the crosses.)
Two of the broilers were raised in cages. No exercise to speak of. They did not vary from my pen raised broilers. My pen is not real big, but it is certainly bigger than cages. They might be more tender, but they are not bigger.
Basically, I think I could have gotten similar size out of White rocks, but they would have been more expensive. I would say that for the money, crosses are better. I would say for the size, crosses are better, even given time. I would say for every consideration except for whether r not they walk around, the crosses are better. These broilers eat pretty well, I do not think the food cost is comparable. The crosses are better.
I am a huge Ideal poultry fan. But I will not be buying the brown broilers anymore. I will be buying their crosses though and have 30 on the ground now.