I've used RAKA for years and never found it brittle. I have had bruises and get the white spot as you describe. You have soft wood as a base with a layer of glass that is transparent from the wet out and a fill coat of epoxy on that. A dent, fractures the fine strands of the glass beneath the fill coat and that's what appears white. However I have never had the epoxy fracture. Usually that's a characteristic of polyester coatings. Epoxy is more flexible than polyester - that's why it can be used as a glue whereas Poly cannot. Epoxy is strong in itself. You can make a casting and actually tap it for a threaded bolt. Because we are all so weight obsessive we have this paper thin coating of it and that's why it can crack - not because it's an inferior substrate. You have to have an epoxy that gets hard enough to fine sand for it to work for us. It's easy for epoxy manufacturers to make rubbery epoxy compounds but then how do you sand it? If you take a 2-1 epoxy and add extra hardner, you will get a rubbery epoxy.