I really liked my "Feed Sack Pack". I might make another just to have a spare around.
If I do, I'm going to modify a frame like this one. That looks a lot more comfy than what I had, which really wasn't all that bad, but the shoulder straps did get to biting pretty hard with load over 30lbs.
Well, these shoulder straps weren't all that comfy around the 60-70 lb range. They worked great in the 30-40 lb range though. Next time I carry that much weight, I will just use my $15 MOLLE shoulder straps. They were designed to carry heavy loads.