I have a question concerning how to manage installation of new versions of workflow features, in case when there are already running instances. It seems on my development machine that after installing new package all running workflows are automatically stopped. It is not a problem now, but how this is going to be handled after deploying to production? Stopping everything after update will surely be problematic.
[EDIT]
I see year ago someone had similar problem, no one knew the solution. Maybe this time it's a bit better?
https://sharepoint.stackexchange.com/questions/83905/sharepoint-2013-workflow-versioning