I have 4 BRs, they are going on 4 yrs old. They have tall combs. They have been through winters, with temps to 0 F, (Sometimes a few degrees lower), and they have never had any problems with frostbite at all. And they have never had any vasoline smeared on them either. And of course, they live in a un-insulated, un-heated coop.
Hey Wthrlady, how's that Wood's coop working for you? The glazing has all but fell out of one of my coop's transom windows. Window has been rattling a bit. But I'm not messing with it now, unless it falls out. Winter has decided to show up here, last couple of mornings down to 10 F, or so. We were up in the 60's coupla weeks ago.