Nope, I don't think Saos are like hardtack - not as you describe it, and as I've always imagined it anyway - they are pretty crumbly when bitten into, but I've never heard of anyone crumbling them up deliberately; they're always made into sandwiches. And while they are good for car trips - they do need a topping, because they are quite dry - they're useless for actually packing in a bag because they crumble everywhere!