I am comtemplating which system to get to cart stuff around on and off the bike. The thing is, what are these things like to carry around? (Not the panniers, obviously, or can I?) The Ventura bags don't look all that comfortable to carry a somewhat heavy load in (5 to 10 kilos) for extended amounts of time. I'm told the back straps are quite uncomfortable for extended periods of time, and I need my hands free, so I cant exactly use the hand strap. What are the GearSack duffel bag things like to carry? Or would I be better off getting a set of Panniers, to carry stuff while on the bike, and a proper backback for moving around on foot?