I'm looking for a project management tool that will allow multiple levels of tasks and subtasks, that can roll-up to a higher-level status. Is Jira limited to just Epic / Story / Subtask? I see that Premium allows the administrator to edit the hierarchy, but I was hoping for flexibility at the user level. For example, I would like to track a system assembly with several subcomponents, where each subcomponent could have tasks or additional subcomponents with tasks. The depth of the hierarchy is variable, not pre-determined. How would I best approach this in Jira?