Good point about the weight, though I would suggest that most people wouldn't be able to carry a CAR-15 much past 8 hours without their pussies starting to hurt. A rifle/accessories weighing 20lbs. versus a slimmed down AR weighing 7 lbs. won't make much of a difference if the person hauling it is not used to carrying a 50 lb. pack plus their rifle. It is surprising how heavy a rifle gets after a while.
I know I hated carrying this thing from hell (203's are great and fun, but not so much when it is in your arms all day long lol)