When buying preowned.. the difference in cost between the Cayman and the Cayman S is minimal. I would recomend buying the more powerful S version.

Over the years the minimal cost of the slightly more expensive S model will be barely noticable...yet the improved enjoyment from having the S model will be long revered..

I'm digging the new 7 speed PDK on the 2010 Boxster S and Cayman S..

If you noticed...road and track got better acceleration performance from the boxster S with PDK than it did with the impressive Audi R8 V8 ...(zero to 60 mph)

The handling and now the acceleration of these two porsches are now world class..

Both the base and the S are great vehicles.....yet I would suggest preowned? the cost differential is minimal and the performance enjoyment over the years will make the S the better choice..

Your Dad sounds like a cool guy.

Let us know what he choose..and fwiw...I'd choose a cayman S over a 911 S ...