I drove a DSG VW GTI and was very impressed with how quickly and smoothly it shifted down and up. For all but at-the-limit track driving DSG > SMG (unless you like getting your neck yanked, but with 420 HP you are already going to give it a big workout
I have also driven a Ferrari F430 at multiple racetracks (yes, lucky bastard) and the SMG/F1 transmission in race mode nails upshifts and perfectly blips downshifts, sounding great the whole time. There is nothing like running 140 MPH down the main straight in 5th gear and then hitting the left paddle twice accompanied by the "whaaaa, whaaaaaaa" double downshift and then charing through a 90 MPH corner with almost 500 HP pushing you through it. Pure automobile delight!