Long rides with load
I use this design especially for commute with 10-15 pounds load (lunch, water, tools, raincoat. lock, etc.). Since the career is my backpack then the suspended factor is not to much affected. On the other hand, a rigid case well attached would cancel any suspension I guess. Any load affects climbing on any bike, so for the CFF. But long rides gets a slight aerodynamic advantage on facing winds compared with side panniers. I prefer the backpack for it is more practical than side packs eg when you park somewhere and have to get to store or to work on public transit etc. A waterproof one is preferred in a rainy region, I upgrade my old one a few weeks ago.