Just to close this thread and hopefully be found later on for reference:
I sent ReDisc this picture and the answer I got back is: "A rough estimate based on the picture is that the discs look drivable/usable...however: According to the indicator, it can be seen that the thickness of the disk has already been reduced close to the permissible limit".
There are other things I can do to obtain the exact wear (weighing the discs), but truth be told, I'm "done" with this specific vehicle. It is quasi-incomprehensible to me that this $25K truck (2011 Turbo with 58.2K miles) has a sooner than later pending maintenance item that can easily cost between $8-$30K to bring up to spec. Can't say that investigating this vehicle and spending on a PPI has been a complete waste as I have learned quite a bit about PCCBs for 958s and in general, but I still struggle in trying to wrap my head around the fact that servicing this specific brake system could potentially cost more than the entire value of the vehicle (something that would not apply if it had iron rotors). I was hoping that the wear on these discs would be much less and I could have really purchased the vehicle.
This truck was never tracked and for the last 4 years in which ±20K miles has been added to it, it has been driven by a lady to do her shopping around town and taking kids to school (lady and her husband own/have owned any number of Porsches...).
For future reference sake, please investigate what version/size of PCCB are on the Cayenne you may be considering purchasing and don't be fooled into believing that these "last the lifetime of the vehicle". As to be expected and understood, mileage before replacement will vary greatly due to numerous variables, so determining how long they will last is a gamble at best. A very expensive gamble that is.
