At the moment there seems to be a lot of DSG problems, mainly Mechatronics units. If you could devise a comprehensive test, and set up a repair loop, you would make a mint. VW seem to repair by replcement, which is an uneconomical practice when out of warranty.
In the future a out of warranty bill in excess of £2k on a an ageing car may be a little hard to swallow. I think a independent from VW repair loop will be set up but it won't be cheap.
The problem is probably a 20p part that is failing, but stripping the Mechatronics unit down and finding it, replacing it and testing is the challenge that transmission engineers have.
There is a 10 year warranty on DSG boxes in the US i believe.