RC releases should not be used in production environments as they are not officially supported.
Please also note:
RC releases may not be safe — RC releases are snapshots of the ongoing JIRA development process. As such:
While we deem these releases to be fairly stable, they have not undergone sufficient testing to be deemed an official (final) release.
While feature development work is complete, some features may be subject to change or may be removed before the next full release.
No upgrade path — Because RC releases still represent work in progress, we cannot provide a supported upgrade path between RC releases, from EAP or Beta to RC releases, or from any RC to the eventual final release. Thus, any data you store in a JIRA RC release may not be able to be migrated to a future JIRA release.