All I can say is in the long run, the dealer is a better bet, and not because I work for one. I work for VW, and there are things like servicing the DSG ETC that you cant do without the VW/Audi gear. They have to be serviced every 60,000. And if they go wrong and they have not been serviced exactally to specs, you can kiss the best part of 15k away for a new DSG. Things like the Haldex unit (the awd diff on Golfs, Passat, Audi Passenger cars ETC) need to be serviced every 30kI had one on an R32 Golf let go at 75,000 kms, serviced by a local garage, never had the diff serviced, the diff alone was 8k.
Just food for thought.