from what I've seen on this and other forums, Sepang is in the lead, followed by Nardo, no silvers, a few whites, just the one red and a coupe of custom blues. It'll be interesting to see if this survey draws out some more people and gets a truer picture. At the moment, my Sepang is looking a bit too common!
Somewhere there is a link to the .de configurator which shows in real time the colours that people are choosing. It's all Audis, not just RS3s but it is quite surprising to me that te majority of cars being specced are non-colours, ie greys, silver, black....relatively few reds, blues etc.