Matt - theoretically it should be quite straight forward. As it says in http://www.openvpms.org/documentation/csh/1.9/topics/installing-openvpms... you can run the database migration step by step up from the 1.4-to-1.5 step. [You will need to run this to get anything done in the 1.5 beta to 1.5 final.]  See also note 3 in the above re the -v -v -v option.]

I assume that there are no archetype or message customisations to worry about.

However, you will have a Java & a Tomcat upgrade to do, and possibly MySQL.  Do the Java upgrade first then remove Tomcat 5 or 6 and install Tomcat 7. That way, Tomcat will pick up the new Java version.

If you have the iron, to run a test system I would be tempted to upgrade to 1.9 beta (or the latest snapshot) and let people play with that as the feature jump from 1.5 will be significant.  I would also suggest dumping their customised invoices etc in favour of the standard 1.9 ones using the letterhead facility.

Regards, Tim G