The first step in upgrading FME Server is to back up config files from the Server, FMEServerConsole and Web Services folders manually. This is time-consuming particularly for the web services folders, not least as it's a lot of propertiesFile.properties files with exactly the same name.
I'd suggest that if you have a default installation of FME Server - so everything goes in c:Program FilesFMEServer - that backup of these files should be automated either to be triggered from FME Server itself (possibly included with the Backup process in step 2 of the upgrade, which backs up repositories/users etc.) or as part of the uninstall of the old version (so a checkbox along the lines of "are you upgrading and do you want to back up config files?" then a corresponding one on the new installer).
Would make things quicker/easier and cheaper.