Hi all. I'm looking at purchasing a new bag. I'm 5'10" and should fit comfortably in a 6' bag. The problem is when I sleep on my back I like to point my toes down (away from my head). In my current bag they touch the end of the bag and somewhat restrict this movement. It's not a show stopper, but is slightly annoying. I'm toying with a 6'6" bag but I've heard the extra length will create a dead air spot which may cause cold feet. And the longer bag is more expensive, takes more room and adds more weight. Any thoughts on this? Thanks in advance for your help.