First TDV8's will probably be 56 plates (MY2007).
The alternators are only good for about 80k miles, but is it a DIY job to change if you are handy with the spanners.
There have been a few cases of turbo failure and EGR problems, but not that many. However RR sports do like to lunch the turbo's on TDV8's
The TDV8 engine and gearbox is much better than the TD6 (GM box on the TD6 is a disaster). The TDV8 has plenty of poke especially if you are towing