I tried it a few years ago after having no luck finding tires to fit an older brass Williams K4s. What I found was that if you take your time, apply it evenly and give it at least overnight to cure, it's a good alternative to traction tires when they aren't available. Use a very small brush and be sure you only apply it to the groove in the driver where the traction tire would normally go. I also made sure the drivers were clean to start with, allowing for better adhesion once the BFS cured.
My biggest complaint about the product is the shelf-life after the jar is opened. It doesn't last long at all.
If I could find tires for my Williams & Weaver locos, I'd use them. Bottom line, BFS isn't perfect, but when the right tires aren't available, it's a good alternative.
