I have had my Buckeyes for 18 months, now. When they were about 13 months or so, I butchered off the roos that were not stocky and dark mahogany colored. I was very pleased with the carcasses I got back from my processor. These birds let go of their feathers wonderfully, white skinned, and tasted WONDERFUL!
I really like these birds, and will have a small breeding flock for sale in the fall as I am just slightly downsizing my Buckeye flock, and getting ready to do some tweaking in the breeding of my main flock. These have always been my favorites. I'm not big on the RIR ir NHR's.
I only had one that had a single comb, but you will get some of those throw-backs regardless of who you buy from, especially if you hatch them out yourself. That is just how genetic work.... sometimes, you'll get Dominiques out of the Barred rocks, since that breed was used to develope the BR's.
As for the "dinosaur-like roar", I have other roos that sound like that, too.... and all chickens will pursue a mouse.