I think the problems you are talking about are configuration related.
If you find your workflow requires you to assign an issue for a question to be answered before assigning it back it sounds like a workflow issue, not a problem with the tool.
We use Greenhopper primarily due to having teams located in different states, working on the same project. Having two physical story walls is too hard in this situation and Greenhopper is a nice collaboration tool that solves this problem.
Using JIRA at my place of work I have found the problem that JIRA does not allow multiple people to be assigned to a certain task.
If I want to communicate with a team member and they are not the original reporter or the assigned user they will NEVER see the question posted. There is no good way of notifying a user that they should answer a question on a task without first assigning it to them.
JIRA with greenhopper is absolutely horrible and has caused many hours of frustration in attempting to get the tool to work to our standards and what we need from it.
If you find your workflow requires you to assign an issue for a question to be answered before assigning it back it sounds like a workflow issue, not a problem with the tool.
We use Greenhopper primarily due to having teams located in different states, working on the same project. Having two physical story walls is too hard in this situation and Greenhopper is a nice collaboration tool that solves this problem.