I'm trying to figure out which size I would...
I'm trying to figure out which size I would need. I'm 6'2", pretty skinny (150 lbs).
I'd bank that you're a M/L torso, but I am worried that your waist is too small and you won't be able to properly tighten the hipbelt enough.
Here is the sizing info for the Kestrel Series.
Torso Length Hip Measurement Pack Size
> 19" / 48.5cm > 32" / 81cm M/L
< 19" / 48.5cm < 32" / 81cm S/M
If that is indeed the case, consider looking into the Atmos 50L--$30 more, but you'll get a pack with better torso sizing AND adjustable hipbelt. The $30 will be money well spent if the pack fits better...
Although I am a woman, I am 6'0" and 160lb. I went with a male's S/M. The hip strap just barely fits me. I have considered wrapping a shammie around the belt for a little bit snugger fit. It is still a very excellent pack. It fit well enough around the hips, but I wish it were a little more snug. I am a 29" waist.