We finally found the time and hardware to move from 1.9 to 2.5. Did a clean install and have been restring course backups from 1.9 into the new courses in 2.5.
However some courses are problematical - the old file system in moodledata was very simple to manage, so that when very large files were required we used Samba to simply drop them in then link to them from within Moodle. (Typically video and music files). Appears that with the new version you can't do that anymore and have to upload from with Moodle - even if I up the upload limit accordingly it will take a long time to reload and then relink some of the courses.
Can't use the backup and restore method as these courses are so large that the backup in 1.9 never completes, just dies at the zipping stage.
AM I missing something? Any ideas?