thomas - just one question/point.
i too had the same idea of storing my audio on a firewire drive, instead of many discs. then my roommate pointed out that you are still relying on 'optical media' with either option.
i feel much better about storing the data on an optical disc and then storing it myself, than relying on a a drive which could be more sensitive to power surges or integrity loss. it doesn't matter if it is a DVD or a CD or a harddrive, they are all optical (varying degrees of stability!)
hope this helps you out, even though you may still go the direction you mentioned.