The only thing which prevents switching from Jira to awesome YouTrack 5 in our company is we can't migrate our work items from Jira. Everything is migrated except estimations and spent times of issues.
Our Jira version is 3.13.
In YouTrack REST API it is mentioned that work items could be imported (YouTrack 5).
So, are there plans to support work items migration included into existing migration based on Jira plugin? Are there any obstacles?