I often use the standalone version of VM for developing ideas and testing my own modules in bigger patches, and later I move to the VST version in Reaper to actually record material. In the DAW it's easy to just turn off the plug in, but I think in the standalone it would also be useful to have an option to pause the sound engine. I often find myself having to switch to a new empty preset, or quitting VM if I want to stop the running patch. You can of course lower the output volume, but it'd be better to not have it use CPU in the background while not in use, without having to close the patch.
Maybe this is not an issue for most people, but just thought it might be something to consider.