Hi,welcome on our forum
Is JEM so far to use it in a live system?
If you really have a JEM 2.3.1 version, then it's surely not stable, because we don't have such version.
The last stable version is JEM 2.1.3, and there will come an update in some time.
We use it on live systems too.
If you encounter any problems please contact us, mostly they are misunderstandings, which can be cleared quickly. And there are some possibilities to make JEM better. Please give always version infos of Joomla, JEM, template...
Our developer of JEM 3 don't like the procedure with alfa-beta-RC-stable. But his testing versions are nearby RCs (This is my opinion). But it's after all for new installations and no updates!