I use a Pop Up 38. It's a good day pack plus it expands so you can haul meat. I keep 99% of my gear in the two top pockets with rain gear and water down below. Not sure how well it would work for an extended back-country hunt.
Definitely visit a store and get your hands on them before you buy. I was about to buy one on the Guide Lite MT frame, but when I tried it on, I found out that the frame sticks up pretty high behind my head. If I lean very far forward, which I have to do all the time in the places where I hunt, then I can’t lift my head very high. That can make it hard to shoot, ride a mountain bike, or even see where I'm going. The Pop Up frame is quite a bit shorter and doesn't do that.
MR also frames come in different sizes. The ones on Camofire are often women's sizes or small sizes and won't fit well if you're over about 5' 6" tall.
Finally, like any manufacturer, MR constantly evolves their designs. The packs shown on the MR site are the latest and greatest but lots of retailers sell older models at a substantial discount.
Okie John