Those Jeeps have both a Mercedes engine + transmission. The swirl motor can be avoided with a new intake pipe with an updated seal. When I got mine it was easily if not more then half the price of any VW or Audi offering of the same year.
If you get the quadra drive 2, you are also getting better awd system then the VAG cars as it has ELSD in the front and rear, so with the torque split you can have all 4 wheels turning on slippery surfaces. The Q7 and T-reg use the brakes to shift the power between the wheels at the front.
The VAG options have way better interiors and I am pretty sure better MPG's though. My only other worry with the T-reg was the chain driven engines, as VW/Audi do not exactly have a great track record. These are looking pretty good now, didn't want to chance it a couple years ago though.