Chris,
The temperature rating for the Down Works Standard is ~12F as you stated (avg of 25F and 2F). The Down Works Standard and Nunatak are not equivalent in warmth. I originally did an estimate in lieu of any published DW specs and miscalculated the bill of material weights for the DW fabric total by .78 oz. On closer inspection I see that the DW Standard's design uses two layers of fabric on the outer surface rather than the one layer I used in my original calculation. Their design is based on unique box baffling without sewn through seams.
My view of hats and balaclavas is that they can be sorted into appropriate temperature ranges and matched to an anticipated trip. I view a balaclava as a "super hat" that I can match to a jacket to achieve the equivalent functionality of an expedition parka for a given minimum temperature.
A balaclava is typically a dual use item for UL backpackers. First, it serves as a jacket hood when the temperatures require it. Second, the balaclava and jacket serves as sleep system insulation augmentation. A temperature rating can be assigned to a balaclava by defining the relevant variables (1 clo winter base layers, and sheltered from the wind) and matching it to the closest equivalent jacket worn while doing camp chores (1.5 MET & 2.0 MET avg).
I am of the opinion that Epic is the most practical balaclava fabric for two reasons. First, when worn under a hard shell they don't have the hood volume to completely cover the front of the balaclava. Many inches of material around the face is always exposed to external moisture and condensing breath moisture. Second, the abrasion from the rubbing between the balaclava and the hard shell won't diminish the DWR effectiveness like it would an add-on DWR.
Down insulation, when used in a balaclava, provides the most insulation for the weight, compresses the best for storage, best conforms to the face and neck contours, and will not degrade from compression and decompression cycles.
The Down Works Standard uses an Epic process fabric on its exterior and has a minimum of seams in the front section which is consistently exposed to condensation. I recommend it because of its feature set, in combination with its low weight, and highest $ per degree rating.

Down Works Standard exterior fabric uses an Epic process
