I appreciate that you're not trying to advertise for their competitor, so I'll be that guy... What did you switch to?
Presumably, one day, we will outgrow that, and need to go to JIRA (with all of its power and complexity), but it would be nice to delay that inevitable as long as possible.
I am happy that I can click a JIRA link and see a page within a second.
Do you host your own JIRA instance and have somebody in charge of running/tweaking it?
Disclosure: I have suggested few features for Restyaboard and its developers implemented them.