One reason the exo works well is the compression straps on the side of the bag are angled. Higher on the frame than the bag, thought being this helps lift the load(compared to a horizontal strap that sags under load). I don't know enough about packs to know if this is a gimmick or really changes the way weight carries, all I can say is it carries weight very well.
Also like how their water bottle carrier mounts to the frame/belt. Even with a 48 oz bottle full, don't really feel it and it doesn't swing around at all. Still easy to grab for a mid-hike swig, though a water bladder is nicer for that. Speaking of water bladder, I also like how they have a waterproof sleeve with a drain at the bottom for that component.
Would suggest copying those features for sure if you're DIYing. There's a bunch more that goes into their packs that make them comfortable, like different hardnesses of foam in different areas but I don't know enough about them to make recommendations.
Also like how their water bottle carrier mounts to the frame/belt. Even with a 48 oz bottle full, don't really feel it and it doesn't swing around at all. Still easy to grab for a mid-hike swig, though a water bladder is nicer for that. Speaking of water bladder, I also like how they have a waterproof sleeve with a drain at the bottom for that component.
Would suggest copying those features for sure if you're DIYing. There's a bunch more that goes into their packs that make them comfortable, like different hardnesses of foam in different areas but I don't know enough about them to make recommendations.