Spoke with NikWax and they don't seem to have anything that is ideal for my purposes. All their spray-on products are recommended for application to fabrics that have been pre-wetted, and I don't really want to wet my cases before I treat them. All NikWax products are water-based, including their boot treatments. They seem to think that ScotchGuard is a better choice for canvas/leather cases, partially because it is solvent-based. As EDM likes to say, investigation continues...