[KNS]

The 996 Turbos seem to be a bit more reliable than the non turbo models, or at least fewer problems have cropped up over the years. They will hold their value better as well. One issue is coolant pipes that crack open at the seam. This is a well known problem that can be found with a search over on Rennlist.

I would much rather have a 996TT over a Boxster or NA 996. It is new enough that I would be comfortable having a PPI done at a Porsche dealer (although I've personally seen them screw up a PPI and would never take an air cooled car to one for an inspection or service). An OBDII scan would reveal much of what you're looking for. You of course want to find out about any accident damage. Ask for the VIN so you can run a Carfax (although not always accurate).