My MY08 TDV6 was experiencing similar behaviour as described by Peter_OZ - 1 second hesitation coming out of roundabouts or changing lanes. At the 10k service the dealer investigated and uploaded a gearbox software patch. Now it runs much better, although now often refuses to change automatically from 4th to 5th when criusing at 60kph. But it can be forced into 5th manually where it will stay quite happily until you accelerate hard.
But in the last week it has started down shifting from what feels like 2nd to 1st when braking firmly (not hard) on a steepish downhill run into one particular roundabout near home. It can be quite violent with the brakes on and then the sudden down shift. No noise or thud, just the downshift.
I also told the dealer the fuel consumption seemed be creeping up, and the dealer also found a patch for the computer. I need to run it a bit longer to see if this has changed things, although the weather has been quite hot in Perth and this is not good for fuel consumption.
