Mac has difficult time writing to FAT (my opinion).
I agree FATXX should be fine for Windows and Raspbian. I will build my external SD/stick/HD with FAT like the boot partition is and post my difficulties (if I run across). I am puzzled as why you are having difficulties. It is also the only part of the SD card that Mac can access easily. After all, the Boot area of the Pi is FAT format and it can easily read and write that. Rpdom wrote:The FAT range of file systems should be fully supported by the Pi and Mac.