Has there been any analysis of the risk of google spidering duplicate content when there are multiple styles available for choosing? One might assume that since all the URL's are the same, there would be no problems. But I wonder since the back end code is actually different, and the front end content is the same, if Google might think these are worthy of duplicate content penalty.
This is my only reason for wanting unregistered/not logged-in (Google spider basically) to see only one style option.