Facelift manual here. after 10K miles it started slipping, albeit infrequently after 14K it was doing it all the time, got it replaced under warranty as it was warped, apparently. I had to and involve Audi UK though, as the dealership claimed the clutch is only warrantied for 6K miles (for some reason), and it way my driving style etc... car now has 22K miles on it and the clutch hasn't missed a beat.
I will not be getting a manual as my next car, i love the manual box, but i suspect that Audi are scrimping on the clutches to save money as they know most S3's will have Stronics.
Two of my engineers have manual Golf R's one is stock and the clutch went after 18K miles, the other is stage 2 and the clutch slipped immediately after getting it tuned (he replaced the clutch with a sachs organic one, and its been fine).
Another engineer has just started and he already owned a manual pre facelift S3, its a 2014 an has 80K miles on it, so far he's been through two clutches, all paid for by him.
in short there is an issue with the clutches on manual S3's in my opinion, i do give my car a hard time once its in motion, but i do not launch it or ride the clutch.