We have just over 110K on our 11 Turbo and previously had over 180K on our 2005 Turbo. The 2005 we still service at our shop, has about 230K on it now, 2 more owners later. Both have been great vehicles.
If you plan to do any towing, air suspension is a must. I tow my 20 foot enclosed aluminum trailer with my Radical SR3, Rolling tool box, spare wheel/tires, 8 full 5 gallon fuel jugs, jacks, etc and the 2011 Turbo doesn't even know it is there, except for the fuel gauge..... it knows....
I daily drive the 11, all year around, and after owning over 40 Porsches it may be my Favorite all around one. It is VERY fast (its a tad modified), handles well, hauls the 2 Boxers to the Vet or park, tows my trailer etc, does everything well.
We see a lot of Cayennes in the shop for maintenance/repair. The 958 seems to require less repairs vs the 957/955. But it is also newer so.... The 958 Interior is also a step up from the 955/957 (which are still good).
We have even built a couple of "safari" ones, which I am tempted to do to the 958 Turbo if we ever replace it with something else.
Cheers