You are kindasorta talking apples and oranges with your comparison. The Falcon is more daypack sized, the REI is a full blown backpacking type pack (I couldn't get the REI link to open to get the size of the REI, and I am too lazy right now to go straight to their webside, but any "backpacking" type of pack that will extend about your head is gonna be BIG). I have both many compartment type packs (in fact, I am currently playing with an el cheapo, made in BFE, rip-off of the Falcon) and single compartment ones. I love both, and hate both. The ones with many compartments are neat, at least on the surface, because you can put different type stuff in different compartments. The rub, at least in my experience, is that 1) you tend to forget what is where, and 2) all that extra material and zippers adds weight to the base weight of the pack. The one bag type bag, on the other hand, can weight less than the other type, but no matter what you want, it is going to be on the bottom of the bag. Always. So again, the best way is to try each out, then go with what works best for YOU...