Rating: 5 / 5
Pros: Hat deserves a "6" on the BPL 0-5 scale--wearing it can off-set the need for one of your clothing layers, very warm--even when damp, doesn't absorb much water and dries quickly, more reliable than a down hat.
Cons: Hard to find--and when you do you will probably have to wait awhile to get one, not everyone likes the feel of wool on skin--you can add a liner (bandana) if this is a concern.
Purchased mine from Bradley Alpinist. (http://www.bradleyalpinist.com/cart/index.php?main_page=product_info&products_id=471)