: ...is it brittle? would it stay attached if the hull was bumped against something

Short answer: there is no downside except price and availability. The flexural yield strength of this family of materials is about twice that of adhesive epoxies, so that would indicate less brittleness. As well as increased hardness, discussed above. Since the matrix is epoxy adhesive, the bond strength should be about the same. I suspect though that these numbers could be approximated very inexpensively by throwing a handful of fine mesh aluminum oxide or silicon dioxide powder, available from industrial casting or specialty aggregate suppliers.