Enjoy your test drives
DSG for me ... this is the future for all cars ....unbelievably smooth & quick gear changes and so so versatile - Drive, Sport Mode, Paddles etc..
The only worry for me would be DSG repair costs when out of warranty if you're getting an older car.
Common problems I've heard of are :
Wind Noise from Wing mirrors / door seals (especially on earlier cars)
Front Doors dropping slightly (in alignment)
Creaking Steering Racks on full lock at low speed.
Erratic rear wiper motors
"Milky worms" on 18" Monza Alloys (under the lacquer)
DV Diaphragms splitting (especially on chipped GTi's) - give it full beans in 3rd and change up to 4th and have a good listen !
Ask whether it's been chipped or not
I'm sure there's a few more, but nothing really common or major !
Also check full history and whether it's an import or not