i've used a balaclava in extreme conditions but the system that works best for me is a super thin smartwool beanie and a thin wool buff. when its gets like under 20, pull the buff over my head and leave it so it covers like 3/4 of my head and ears and tuck the neck part in my shirt. then i place the beanie over the buff and i form a type of balaclava.

i've always favored modular systems like that. this offers me the ability to keep my hears and head extra warm and still protect my neck. if i get too hot, on my head, i just pull on the buff and now my ears are only covered by the hat and not the buff + hat and still keep my neck warm.