I carried an ILBE this year on my first elk hunt. I bought it used for $35 dollars (after some condition issues) and immediately cut off anything I could. Ended up carrying it at 6.5#.
Never needed it to pack out meat, but I can say that at probably a little over 40 pounds of gear, including water, it wasn't very comfortable. My biggest gripe was the waist belt is horrible. I considered an HPG belt even before the trip, but didn't. The load lifters are also too low, tacked onto the shoulder straps. I think the tacking can be cut, increasing the lifter angle. But I was afraid to do that in the field.
It worked, but I'm currently in the market for a used duplex. If we had to pack out 80# a time or two, it would have been horrible in the ILBE. As a day pack it was good enough.
Anyone looking to sell a 26" duplex, small belt?