Whilst I was there and before I saw this I spotted a Matt Black A8 and that looked cool. Then around the corner 5 mins later there was a Matt Black BMW X6 and then I spotted the RS4. It seems a popular mod over there!
As for your question regarding if they look good in the flesh...........Yes they do but my favorite was in fact the A8 over the RS4. However I think the best Audi model to have in Matt Black is an A5 or S5 for sure. There is an urge to write on them in chalk though!
I also saw a B6 saloon with a B7 front end. I did take a pic but it was quite dark and I haven't looked at it since I got back to see if it was done using genuine parts or not.
Also saw an older TT with a big grill front end that looked really nice.