DSG is not limited to the TDI engine but is also on the V6. My local dealer said that they worked hard to get the 40K mile DSG service price down to around $220. For DIYers, you can do it yourself with the replacement fluid being the most expensive part of the project.
The V6 requires 91 octane gasoline and the TDI needs diesel which are both more expensive per gallon than 87 octane which the 2.5 uses. This increases your annual fuel costs, slightly, for both the V6 and TDI engines.
There are countless threads/posts on changing the oil before the 10K / one year interval recommended by VW for all engine models. Doing anything sooner than VW recommends will push up your maintenance costs.
When I purchased my car last year I started to put together a maintenance spreadsheet and tried to located intervals for coolant, etc. Other than the standard change your brake fluid every 2-3 years and what's in the manual, some of the intervals are not defined (engine coolant is one of them).