Thanks for the update, Carlos & also for the several initial follow-ups, Mojave.
I too got stuck into reclaiming a neg from the FP-100B and made the same discovery that you guys made. Something along the lines of, "Where the heck did my negative just go to?!" I did end up with one 50% usable neg, but haven't bothered scanning it.
HOWEVER, thanks to Carlos' tip about removing the top layer only by washing it and not touching it, I will definitely give this a go. One question though, I would always take the black backing off with the bleach before trying to wash off the top layer of goop. Is there any reason why you didn't do it this way round?