Munch:
DD formatted HD floppies can become corrupted very quickly. Something to do with HD floppies requiring stronger electromagnetic fields to be written to properly (or just the other way around).
Floppies have a reliable lifetime of about 10 years if I'm right, just like video tapes. So using secondhand floppies for critical data might also not be a good idea.
I have no idea where to get new DS/DD though :-(.
