My wife and I use those, and while i like them for their simplicity and light weight, I don't think they'll help much. The bungee is a relatively lightweight elastic strap. and basically just pulls down on the bag so that the hooks do not easily bounce off the rack.

They do have Velcro that wraps around the tube that the hook sits on to avoid bouncing off though.

I's just do something similar to what lee mentioned regarding an added bungee over the bag.