I forgot to add, some people had found that flashing a 1004 with the 1008 firmware gave them better media compatibility than the 1004 regular firmware.
But that was around 043 - 048 versions. maybe the later 1004 firmware versions have caught up.
I believe that some people have flashed a 4x Lite-On drive with the firmware intended for its 8x brother and got it to work.
8x drives are so cheap now it hardly seems worth risking destroying a working drive though.