I could be barking up the wrong tree completely, but I vaguely remember seeing an 'abaqus update' command in the release notes for 6.3, which I believe is used to transform the odb file from the old format to the new..... I haven;t got the manuals to hand to check this though... sorry if it turns out to be a dead end, but it may save time if it turns out to be true.
GJS