Haven't seen much about zpacks sleeping bags on here. On paper they seem really good even for the money considering how light they are. Is there any particular reason they aren't recommended on here? Are they not durable or not as warm as their rating or something? I've got a cheap Amazon down bag that's not awful, but not great. It's under 3 lbs and good to freezing temps. It's tempting to upgrade to either a sub pound 3 season bag or a 4 season that's still significantly lighter than my current bag.