Barney, I too like the idea of carrying other items using the rack. Moving the Thetford grey tote I have is a great option to reduce congestion in my covered truck bed.
The responses in the Flagstaff forum are somewhat "cooler" than those here. Still, no one actually has related a ladder failure first hand. Don't know what these ladders are rated for but assuming a 250# person with some margin for dynamic loading as the ladder is used for access to the roof! it should be able to bear 50 - 60# of bicycles of load that is flatter to the ladder thereby loading it more in shear as opposed to pullout loading on the rear wall.