I was working on a map with a 2nd floor and thought it would be easier to duplicate the first floor and just alter what was different to the map. While you can obviously export the image of a map to use on another you wouldn’t have access to the full ability to edit it like the normal save file where every thing is still in layers.
So my suggestion of a feature to consider is the ability to back up or duplicate a map save file. Far as I can tell the save function always over writes the same file, even if you change the map name. Not only would duplicating maps make edits on small differences between similar locations but also as a nice insurance of a complicated and detailed project you might be working on.
You never know when some big mistake screws your map up beyond the undo tools ability to fix, or even just a file could get corrupted. Better to lose some of your work than all of it because you only had one save.