Passat, Liberty or Mazda 6?

I am looking at updating my vehicle and have narrowed my search down to three vehicles, the Volkswagen Passat 132TSI, Subaru Liberty 2.5i or Mazda 6. My current preference is the Passat, as I like the look of the car and the features but I am concerned about the DSG transmission as I have heard that it can be a bit sluggish. I have read there have been some issues with the transmissions in VWs. Would I have any cause for concern? Has VW rectified these problems? I do a lot of kilometres and open road driving so performance and reliability are key criteria.