As you probably know, FAT32 with vfat is supposed to preserve case but be case insensitive. But I have had some issues with this on Linux. For example, I know when I wanted to create a directory (or maybe it was the file) called KNOPPIX on a FAT32 partition it ended up in lower case. It seemed, however, to be tolerated, as the KNOPPIX system booted just fine.
I know this isn't a definitive answer, but I hope it is helpful.