I had a brief correspondence with Brian (Sector101) which have built flash-rom modules for the Yamaha range (Sy99/85/th500 as well as for the EX5/r/7 range) and he told me that it was not possible to do due to the chips being to old. If you guys can prove that wrong, i'll be the first in line to purchase what you come up with for sure :-).
br
Dan