Michael Morris wrote a review of Arc'teryx Axios Backpack 50 - Men's - 3051-3661cu in on December 3, 2011
I bought this pack for a trip to Ecuador over the upcoming holidays because I figured I may be able to cram two weeks worth of stuff in it and still carry it on the plane. Hopefully that works...
Anyway, I got a chance to break it in the other day on a 2 day, 30-miler through some scrub land and oak hammock in central Florida. It was 85 degrees during the heat of the day, and I was a sweaty mess, but the bag was the least of my worries. I have the 'tall' size, and at a long-torsoed 6'1" it fit me very well. I had about 27 pounds in it when full of water, and it felt like I was carrying clouds around because the weight was so easy to manage. As hot as it was, I knew I couldn't expect to keep my back dry, but I got some nice airflow back there too. It took a little bit of a beating climbing around on some live oaks and running through palm scrub too, but held up very well.
Also, the top pocketing with its multitude of zippers and compartments was fantastic.
So, for initial impressions I'm quite pleased. I'll report back after Ecuador and see if there are any updates that need to be authored, but I'm very happy with the purchase thus far.