Yep, like they said, it's going to look a little saggy, but the back is stiff enough to keep it out of your spokes. The extra carrying room is nice, but after riding with 4 large panniers, and then paring my gear down to two large panniers, I decided that I'd rather distribute my load across the bike, so I got smaller panniers (Front-Rollers) and use them on the rear rack. Everything else goes in more bikepacker-style bags: frame bag, handlebar roll, fork cages if I really need them. If I were to return to a four pannier set-up, I think I'd go with four Front-Rollers before I'd go back to the Back Rollers. If I don't need the space, I don't want the biggest panniers.