I think it would be very helpful if it was possible to arrange the gradebook manually. At my school, registers are not done alphabetically but by number. It would make things much easier for me if I could reorder the students in my gradebook so it matched the number order that the school uses.
I don't think this is possible, but if it is, please tell me!
Otherwise, I think this would make a good change. I work in a school in Thailand where the student names would not be written in Roman script thus alphabetic order is not often used.