There is rose comb Leghorns. Personally I don't think you can get a much better layer than a Rhode Island Red, and they can be had in rose comb also.It's interesting that there are quite a few hot weather chicken breeds, but no really- cold- weather egg laying breeds. Single combs are everywhere... sigh.
I've never had a problem with straight combs other than the tips of the roosters combs getting burnt and not bad, heal right up like they never had it in the spring. And we can get a few months of subzero and -25 or worse windchill. Good ventilation in the coop.
I had the red sussex get some pretty painful looking frostbite on their wattles, they were dragging them across the ice. Giant's have smaller wattles and didn't phase them.