Suggsted SD Card file system

Hi,
being my first post, I'd like to thank the developers of BootMii for this great app.
I was fortunate enough to avail myself of the possibility to install it in boot2.

Now, I'd like to ask if BootMii prefers any particular file system for the SD Card to be used for the NAND backup.

I'm just asking since I could notice that on my Sandisk Micro 1Gb (with adapter obviously) the backup process lasted longer with the card formatted in FAT32.

I run another backup with the card in FAT16 (16kb cluster size) and the whole process was much quicker!

Also, I'd like to understand if preference should be given to any particular cluster size when formatting in FAT16 (or even in FAT32).
Does the file system and cluster size affect in any way BootMii operations? What do the developers suggest?

On a side note, I also experienced some occasional issues with the feature available in BootMii menu to browse the SD Card.
Sometimes, when trying to browse the card, the file browers shows it empty and all I can do is pressing the reset button twice to get back to the main menu.

After reboot, the card is properly browsed without issues... This happened with the card containing my nand.bin but also with my other regular size (no micro/no adapter) Sandisk 2GB SD Card.

Thanks again to the developers and this great forum!
Cheers