I noticed that most of the games I've ported expect to save like a normal file, so having a filesystem for the sram would make that easier. The sram is small, so I have the cluster size set to a single sector. Libff has been set for a while to make only one FAT when it's used to format the drive, and when you format something that small, libff naturally uses FAT12. All told, you lose maybe 4 sectors to the volume table, FAT, and root directory (out of 511 sectors total).