We are currently running JIRA version 5.2 and would like to upgrade to a more current version ~ 6.1, 6.2 or 6.3. In reviewing Q&A on this site, it appears there have been issues when trying to upgrade from 5.2 to 6.3, as well as 5.2 to 6.1 and then to 6.3.
Question #1 - What is the recommended path to upgrade JIRA version 5.2 to version 6.2 or 6.3?
Question #2 - Is there is comprehensive comparison chart available outlining the new features available in each of the versions subsequent to v5.2?