Windows Technical preview allows you to perform differential exports of VM’s using checkpoints.
What this means is that you can export a VM and at later point perform a second export of the VM. However the second export won’t be a full export it will just export the changes since the previous export and link it to the previous export in the form of a AVHDX (checkpoint) file.
Very useful, could even be used as a poor mans backup. Also pretty sure that we’re going to see backup software take advantage of this new feature.