I'm about to buy a 16GB touch for my daughter but am confused about the versions on sale. I've seen model numbers MA627Z0/A & B. I believe early versions (A?) can have the software upgraded, both the firmware and the January update (for a small fee) but wonder if there were any teething problems on early versions that have been improved in the later (B?) version that make it worth buying? Otherwise it seems the A version is cheaper even after paying for the Jan update... What do you think?