All the save files are handled by the Steam cloud. With the current implementation it is not supposed to be possible to create backups as this will lead to exploits. The developers can not be held responsible for messing with the files created. With plans to make changes to the dedicated server implementation in the future, there may or may not be options to do so.

I suppose reading this that it is not possible to move the save file from one computer to another ? I can't find the save folder...