I strongly suggest you break down your pack usage: How much time will be spent in day pack mode, versus a bivy mode or full pack in/packing meat out mode. Most packs are compromise solutions to different problems of overall weight, pack space, silence and durability/comfort with different weights.
The following are based on my use of the mentioned packs:
Not trying to pick a fight here, but if kevsuperg used his Eberlestock JustOne to pack out 100lbs of meat (rather just as a day or bivy pack)and found it comfortable, he is a better man than me. Great day pack/3-4 night spike camp pack. Sucks under load due to a horrible belt and lack of load lifters. Heavy empty weight for what it can carry. If you have a short torso, you may be able to make it work, but couldn't, and i learned that packing a moose out years ago.
The OPW is a great daypack, and you can easily get a 60# load of meat out in relative comfort. Quiet, durable and a well thought out design.
Put more weight in it, and the light stays without a cross tie at the top will show you how much a pack can barrel under load. You can fab up heavier aluminum stays, and rig a cross piece, but all you have done is made a heavier modified Kifaru Bikini style frame.
A new Kifaru pack is great, if you can justify the cost to yourself. The Mountain Warrior is a great bag (but pretty big for daypack use), but the 500D is noisy, and unless you are packing a lot of weight on a regular basis is a bit of overkill.
A used second generation Kifaru Duplex can be had cheaper (as can a Gen 1), and you aren't sacrificing much (bare pack weight). Used Stone Glacier Krux Frames are a great deal (if you don't have a flat back profile).
A Marine Ilbe (if the torso fit is right) or an Arc'Teryx Bora with a Kifaru Duplex belt on it (that is the right size) will handle all of the weight you can throw at it. Heavier than an SG or Kifaru, and not as glamorous.
If you are on a budget, spend more money on boots and less on a pack for your first kick at mountain hunting. And remember, like boots pack FIT is everything.
Take five days and try a backpack style hunt/trip where you are and see if it fits for you before making the big cash committment. It looks great from a distance to a lot of guys, but it really isn't for everyone, and i have seen a lot of gear sold really cheap by folks who learned the hard way that it wasn't for them AFTER they dropped the money.