Just bought a Pd140 in october - ok its a Jetta, but same engine!
Its all about each individual car and how its been looked after - the oil feed pipe has loads of nasty 90 degree corners and it the oil hasnt been changed enough then they can get clogged and end up starving the turbo of oil = bearing failure normally.
There is no way to tell if a turbo is on its last legs unless there are signs of wear already. Check the service history, make sure there are plenty of oil changes - every 10K with longlife oil I was told was recommended (the longlife you normally get the oil change done every 20K, but this is way too long a service interval if you want your car at peak running.
If you want to keep the car running well a set of the darkside oil feed and returns would remove the worry of the clogged oil feeds (as theirs is a flexi hose) and good oil and filter every 10K. if it lets go in the future then you can always upgrade...........