I get the impression that these engines wear out quickly

[1JB]

Make no mistake although overall these engines should go for well over 100M miles if they do have a big problem like the intermediate shaft failure and it's out of warranty it will cost you an arm, leg and your first born. Although failures like that are out there they are no where near something like the failure rates on the early Acura MDX transmissions for example.

[Brucelee]

We don't know how many Porsche engines fail prematurely and Porsche is certainly not going to issue any data.

Anecdotely, there are more than a few IMS failures in the 1997 and on engines.