Personal preference borne out of a desire to not freeze my a$$ off more than necessary--been there, done that. I often use a hip pack if its warm, but as soon as things get cooler (mid to late october usually) I can't fit what I need to stay warm if I need to stop for a bit in a hip pack. 95% of the space in my pack is taken up with a couple extra layers--warm hat, insulated gloves, a small thermos, and at least one extra warm layer. it weighs very little, but it is bulkier than I can manage in a hip pack. I have friends who carry a hip pack, but they have less flexibility in adding and removing layers since they have much less space to put it if they take something off--they are either unable to stay warm if they want/need to stop for any reason, or more prone to sweat because it's harder for them to remove layers, and consequently they are less able to deal with keeping themselves warm for a full day out. If it were only a short easy trip to a stand I dont think it would matter much, but if your typical trip involves multiple miles, steeper terrain, etc I can't see not having the option to take most of my warm clothing off and have a place to carry it. Also, I usually hunt with an 18l pack--it's not an excessive size, but its still too small for any of the warmer isulated bibs or jackets that lots of people use. Quiet-fabric whitetail gear for stand hunting is crazy bulky. For you guys who only hunt with a hip pack, how do you manage carrying everything to a stand that's a mile or 2 miles up a mountain when it's well below freezing?