I don't know the details, but NTFS on such an old Linux system, cannot be a good idea.

Even on modern systems, the rule is: if you can avoid it, don't use it.

If you have problems with FAT32 then you should fix those, because it is not "easily to damage", and afaik it has only 1 limitation: max 4GB filesize.

Generally speaking I don't see why ext3 shouldn't be possible (not so sure about ext4 because of the age of the N900 kernel).