Like Austin I've got the GL Great Basin but coupled with Ortlieb Rack Pack and Famsa Tankbag. As he has said the Great Basin is not 100% waterproof but it does the job for me even though a little pricey. Have you considered Ortlieb as they do the MOTO Saddle-Bag and MOTO Speedbag which look sort of similar to the Siskiyou Panniers.