What are some of the good ultra lightweight winter jackets, full zip? I like the Marmot Zeus but it's a little heavier than some other similar jackets like the Montbell Thermawrap jackets or the Patagonia Nano Puff Jacket. What else is good in this category? I'd prefer synthetic but will look at what's out there in down also. Preferably under 13 ozs (really under 10 is more like it).