A nail file is essentially the same thing as a suede brush - the one with the metal bristles. In fact, it may be even more gentle than that. I am so glad that tip worked!
Oh, I use Wilson's leather protector on any leather or suede items. It has never darkened anything yet (even white things) and I've never found anything better for water resistance and keeping stains on the surface for easy removal. It is pretty cheap, too, and available at any Wilson's store or outlet or online.