I'd definitely go the warmer bag. I too have the Everest, like Kiwi Hunter obviously has, and have been cold in that sleeping in a caravan in Christchurch when it got to -12 (aluminium isn't a good insulator). Being a skinny, bony little squirt I roll around a lot at night and prefer a narrow bag so that when I roll over it rolls with me keeping my nose pointing out the face hole and avoiding moving warm air out and cold air in.