If you're considering the Fly Creek 2 anyhow, and money is no object, look at the "Platinum" version - same space, half a pound lighter, lots more expensive. Beyond that, I'm no help - I've never thru-hiked or even taken a trip more than a week in length. I'm not a big fan of the Fly Creek series (due to the end opening); I love my Copper Spur UL1, but recognize it's half a pound heavier than the Fly Creek UL1.