Can't speak for the FASS - IMO they are overpriced.
I personally have an AirDog and have installed many more. They now mount parallel to the frame (older ones hung out perpendicular) and can be mounted on either side of the frame rail. We usually mount them inside and they are tucked up out of the way nicely. They also come with a 1/2" supply tube/draw straw which you have to purchase serperate with the FASS. They are quiet, the truck draws fuel through fine with them turned off, and AirDog does include plenty of hose for you to mount it pretty far from the tank. I've used the left over to install PPE and other lift pumps and still have alot of left over line (from installing multiple AirDog kits). For $499 shipped you can't beat it IMO.