Comfort/Fit
The Perfect Fit back is able to maintain flexibility advantages for light to medium loads and has enough padding to comfortably support those loads. The bag has all the adjustability that one would expect from a Kelty bag. The shoulder straps don’t have too much rigidity besides the one inch wide webbing and the padding is somewhat soft. 

Storage
The lack of a traditional brain (The Redwing 50 has a simple horseshoe zipper opening) takes away the vertical compression feature found in other bags. There isn’t much horizontal compression and it doesn’t expand out well. The water bladder sleeve also works for a laptop computer. 

Stability
The Kelty Redwing uses a lightweight rectangular frame that holds light loads well. With heavier loads, most testers prefered something with a less flexible frame. The side compression straps allows users to a loads of various of shapes. 

Durability
The exterior fabric on the Redwing is durable, apart from the water bottle sleeve. The zipper pulls aren’t reinforced. Besides the highly-visable metal hook-and-clasp on the back that doesn’t get yarded on very often, the buckles are a lightweight plastic construction.  

Extras
The non-adjustable side sleeves don’t seem to add any functionality while being a distraction. The zippered interior of these sleeves aren’t big enough to be worth it. The water bottle sleeve is too small for 1.5 liter bottles. One neurotic tester really appreciated the elastic ties at the end of each strap that eliminated flapping ends.