By default, email drafts are saved every 1 minute. So far I have experienced no issues here, and I receive over 200 emails a day, so I am a big user of this module.
Are you still experiencing this issue? Have you tried debugging your system in case it is a server setting issue?
By the way, the 3.1.X.X are much more stable than the 3.0.X where we performed core changes, so it would be safe to go there. In fact, we always suggest backing up all of the data first before performing an upgrade just in case of anything.
Best regards,
Francisco