I'm assuming we'll be able to do a direct upgrade over 13.3. For other versions a clean install + device migration might be the safer bet. 

Here is a link to the recommended upgrade path by QA to v13:

http://www.soti.net/mc/help/v13/en/default.htm#Setup/UpgradePath.html

Eventually, this will be updated in the v14 documentation to say which builds can safely upgrade to v14, but for now if you are on v13.3, you should be able to upgrade to v14 without issue.

I can confirm I've succesfully upgraded to v14 from v13.3 without issues.