I am using VM for a while now, most of the time to have alpha, ctp, beta...
My issue was that my main VM was starting to be really big: 8.5Gb and I had to do something to save some disk space.
If you are like me and you are using Groove. I recommend you to read Marc Olson's Groove "12" Blog. Tomorrow Marc will blog about the integration of InfoPath and Groove 12, such an integration is so promising.