This sounds like a great idea, I've been using something simliar myself.
So let me explore the concept a little further.
Let say I'm building 4 machines over a one year period. I build the first machine as a proto-type. In the process I find things about the cables that I would like to change for the next 3 machines. But, it's too complicated/expensive to go back and update the first machine. So, I export the project file to .xml, check it, tag it as the machine 1 release and continue on with my updates for machines 2, 3 and 4. At some point later, I decide I have a critical change I need to make on machine 1. I can go check out a copy of the machine 1 design release. But, how do I pull the old machine 1 release into VeSys? Do I export and commit the current project, delete the current project (File/Delete_Project) in VeSys then import the machine 1 version of the project?
Per our conversation this morning it sounds like I answered my question correctly.