Isn't the other limit the fact that FAT32 maxes out at 2TB at 16kB clusters? Even so, HFS+ shouldn't have this limit, right? So if you have a Mac and can format it in Mac format, it seems like you can go over 2TB up to 16TB since the partition limit would be the same as with Windows (16TB), but they don't have the file system limitation that Windows FAT32 does?
If they formatted the iPod as NTFS, I would've thought you could exceed 2TB even with MBR if sector size is 4kB each instead of 512 bytes.
But then, I don't have a Mac handy to confirm this. It seems that you're all referring to Windows where we know the limit is mostly due to the file system. If you can use Mac > 2TB, it wouldn't work in Windows since Windows would force you to format as FAT32 even if you have a read/write driver in Windows.