by Lawrence Ng.
Have another idea for you William.
Install a base 2.5 or 2.4 on another machine.
Backup your 2.3.x course and restore it to the base 2.4 or 2.5 moodle
see if your enrolments are there... if they are, then you can be confident to upgrade with a reasonable amount of certainty that it would work.
http://qa.moodle.net/login/index.php