In reply to kingjam:
I've used the 45L version for a bit now, it's a great lightweight pack. As Bluebird mentioned it's not adjustable in the back length. I'm 5'10" and it fits me fine. I quite like the 'modular' aspect, you can strip off the compression straps to create a very clean pack. As already mentioned the water-resistant zips are sticky and don't really ease up with use but they've not broken and never yet failed. The cord pulls are really skinny, I added thicker cord for easier grip. The 45L version carries weight well, the straps are a little stretchy and remain comfortable even when bearing a full load. And it's orange... so cool!