As my bio indicates, the managers are tracking AGILE projects using a "free" version ($10 a month) and want to move to the enterprise version. It appears that use of the trial version would work via an XML export/import but I don't know if that is possible with from the "free" version.
Regarding specifics - It is reasonable to assume the database schemas are the same if an XML export/import can be used - especially if triggers populate default values for not null columns that may be different between the two versions - but are there differences in column lengths, datatypes that are automatically changed in the XML import, stored procedures, and most important, are there any columns in the enterprise version that have significantly different or even nuanced different from the same column in the "free" version?
Can you use the Oracle's Data Pump export/import utility instead of the XML? And will SQL Developer/Toad/Enterprise Manager Express | Grid Control be used for managing both "free" and licensed versions. For Microsoft, will the XML output be used to import into both Excel and Access as well?
There are no differences in data between the free and enterprise version. Having said that, you can also use the Oracle utilities to export/import data to the new version and just point the JIRA instance to the new DB.
Do it in a test instance since you are attempting it for the first time ;)