We used and abused these packs while climbing and hiking all over the front range and Western Slope of Colorado. We used them daily to carry our things around town and on many climbing trips. We traveled with them, hiked with them, and climbed with them side by side to see how the compared in the lineup. We sent three of the packs to Haiti on a hurricane relief trip to see how they'd function as personal items and while trekking in humid climates.
We also employed our standardized backpack volume test, pioneered in our Mountaineering Pack Review by Ian McEleney and spreading to our other pack categories. See the "How We Test" portion of that review for the full breakdown of the methodology we employ. Throughout this process, we learned which packs were comfortable, which weren't, and our first impressions were totally upset.