I am Kifaru owner. Been using an Alps brand traverse, Nimrod wilderness pack, and assorted military surplus packs for a good bit now.
All work good and got the job done. I'm not going into the military packs. They just work. Now, I can say easily that I liked the traverse pack. Carried a bit of dead stuff in it. It does well until you get it upto 70 pounds. Then it goes down hill quick. Nimrod worked good too until about 60 pounds. That's fine as they weren't designed for anymore than that. I never remember being very uncomfortable with hunting loads. Where they showed their deficiency's was in heavy ruck training.
I told you that to tell you this. There is no comparison between them and the Kifaru. None. At 20 pounds there is none. At 80 pounds, get outtahere. It will take experiencing it to really believe it. But, that Kifaru hip belt and suspension takes those heavy loads and puts it where it belongs. When you are carrying 80 pounds up a steep grade briskly and, the only burn you feel is in your hips, gluts, and thighs versus your whole body aching and in pain, you know you got the right one.
If you intend to keep your loads light, you'll be fine. If you intend to suffer of sorts through heavy loads, you'll be fine with the Alps. It will do the work. However, if you'd ever strap a Kifaru pack on your back that was set up for you, you'd never spend the $300 on that setup. You'd instead sell something and save to put the Kifaru on you. Heavy loads is hard work in any pack. I'd rather work hard and get it done instead of hurt and work less efficiently.
I've been where you are at. I was the guy for years that said "No" to the price. On forums and to myself. Until I caught myself last year setting in camp the last day of bow hunting because i was dreading carrying a deboned deer 4 miles. So, I made the commitment to buy an upper end pack and would NEVER willingly go back to what I was using after doing so. If I get cancer again and, have to sell my stuff again to pay the bills, the Kifaru pack would be the LAST piece of gear to go. And, I've only been ruck training with it for ONE month. Just find a way to do it. Skimp on clothes, optics, arrows, something and make it happen. You'll be so glad you did.
I applogize for typing so much. but, it is that big of deal to me now I have experienced it myself. God Bless