http://forums.bowsite.com/tf/bgforums/thread.cfm?threadid=438748&forum=2
I used the 3500 EXO for hauling out two elk last fall. It did the job. Great pack. Fit well and balanced the load well.
I sold it and picked up the new Kifaru Mt. Warrior with a Duplex Frame. Hauled my bear just last month and I may never look back to another pack. The Kifaru just fit perfectly. No weight on my shoulders. Very solid and versatile.
IMO both companies make a great pack and you can't go wrong.
A pack does need to fit you well, but with today's offerings, a guy should be able to make any pack fit well.
My mountain pack of choice continues to be a Kifaru Mountain Warrior with a modified bikini frame. It will carry all the weight I can carry comfortably and goes down to nothing in daypack mode.
The new Kifaru frames have "peaked" my interest but my current setup is dialed in so I'm not going to mess with it.
If you want a pack for a lifetime, buy once, cry once and get the Kifaru. If you want a more economical pack that will get the job done get the EXO.
I've bought and sold 4 Kifaru packs, all G1-G1+. All were relatively light and comfortable. What they lacked was the minimal organization I preferred. Organization could be added by attaching $50 bills (pouches and pockets) to the outside which resulted in a heavier pack and more straps. I also did not shoot my longbow well with the duplex frame but that may just be me. I do think things have improved regarding organization features at Kifaru but I've moved on. (But I'll never sell my Scout.)
The Exo provides some nice out-of-the-box organization features without being gimmicky. Easy to set up. Comfortable, more so once I swapped out the belt to the right size. It came in the pack size I wanted, ~3000 cu in with elk quarter capability. I see the Exo as a Late Season with a few extra organization features and a load shelf. Long-term durability? Don't know but it should out last me.
Both Kifaru and Exo will get the job done. It may just come down to nit-picking the features you prefer.