The info on the update is all at Fostex. Clipped from the update info pdf:
"mr8_v120_note.pdf
Notes on MR-8 Software Update to V1.20 or later
Updating the MR-8 software to V1.20 has drastically improved the CF card WRITE/READ
performance, which enables to use CF cards which were previously considered to be inappropriate on
MR-8. Due to the difference of internal configuration in the created WAV files between the software
V1.11 or before and V1.20 or later, as shown in the illustration below, MR-8 offers only the upward
compatibility. We encourage you to update the MR-8 software to maintain the compatibility as well as to
obtain a widely given choice of CF cards.
Created WAV files using the software V1.20 or after are not
recognized on MR-8 with V1.11 or before software at all.
The LCD bargraph meter does not indicate a signal level on
all tracks 1 - 8 as if no material was previously recorded."