Cass: AFAIK, it depends on type of protection, if its just 'enter number on page:' it should be very similar to .adf
but if its some tougher, you could only use it in UAE with plugin. I think I've heard somewhere that people had some success with WHDLoad+IPF..
it would be really nice if there was some cheap way to write them onto real floppys so that we could restore our fading originals.
IIRC, even with those tough copy protections, usualy its not in the whole diskette, so you might overwrite the part of your original game that is not readable (assuming there is no physical damage)