The 750's are fine if you don't overfill. If you do they will put pressure on all sides of the locker and could cause some damage. I didn't find much of a difference in the wake from the 455 bag. The 455 is sized to fit the locker and you don't have to worry about damaging anything. I went back to the 455 bag (piece of mind). The 400 bag is cheaper, but is not sized right. Too long and too short. We often put some addition weight (400 bag) on the seat, when we do not have any human ballast.