Used Refractainstaller last night to do a conventional install on an 8 gig usb stick, ext4 and a small swap partition, worked beautifully, despite only being usb 2, it runs faster in every way and boots quicker than my hard-drive install. I imagine an SSD HD would be faster, but so far the stick install puts a plate-spinner to shame.
If I had usb 3 i'd run like this all the time. Also seems like an easy way to run another "build" partition or more. (I don't use VB to build or at all really, just one of my quirks).