The stability of a large saddlebag depends on how well it is mounted. The Carraduce bags are mounted transversely and if the straps are buckled on the inside of the bag (rather than on the outside as shown in many photos) so that the bag is tight against the saddle and then the third strap pulls the bag tight against the seat post then sway is tiny. The longitudinal mounting if the bikepacking bags might amplify any sway and I have seen videos where they bounce about a lot. But I imagine correct mounting would minimize that and they they also work well when used correctly.