Regarding differences in heat tolerance.
While a peacomb doesn't have the same radiant opportunities as a single comb, I believe that the down may also contribute. It has been my observation that Ameraucanas and Ameraucana mixes (as are some Easter Eggers) have a different type of down and seem to hold heat more as babies and adults. I don't know how to quantify that difference. I have noticed that they seem to pant more than other breeds/mixes.
While a peacomb doesn't have the same radiant opportunities as a single comb, I believe that the down may also contribute. It has been my observation that Ameraucanas and Ameraucana mixes (as are some Easter Eggers) have a different type of down and seem to hold heat more as babies and adults. I don't know how to quantify that difference. I have noticed that they seem to pant more than other breeds/mixes.