I agree. Mine live in an uninsulated coop and I don't provide them with a heat lamp. Out of all my poultry, they'd always be the ones out scratching around in the snow and they laid quite well in the cold. When its super hot outside, they sit around in the shade and pant, and I don't see many eggs.
I agree, the walnut comb , (as with rose combs ), makes them more 'cold hardy 'than star comb breeds. Heating coops can make them more susceptible to the cold , and weaken their immune system. So long as they have a covered area to keep out of the rain and a draft free , well ventilated coop they are happy.