I've been toying with the idea of replacing my ArcticShield 0 degree synthetic bag(3 lbs). After looking through all the usual US manufacturers,(Marmot, Western Mountaineering, Big Agnes, etc) I thought about manufacturers in Europe. After looking through some of them, I ran into Hispar sleeping bags, manufactured by Peter Hutchinson Designs. Some of these bags seem unbelievable. Like a -46°C (-51°F) bag weighing only 3lbs 4oz? Check them out here. Any thoughts?