I just had the opportunity to compare a 911 GTS and a 718 Spyder (both PDK) on a racetrack. Myself I own a BGTS 4.0 with a manually shifted gearbox.
First : all these cars are sportscars but no racing cars. Therefore (for me) it doesn't matter, which car will be a few seconds slower or faster on the Nurburgring North track. If money doesn't count, drivers feeling is the only important thing. And regarding this, I found (for me) a very clear decision :
If it is the only (daily) car, I would definitely prefer the 911 GTS. It is comfortable, smooth and elegant to drive. The 718 is much more direct, louder, needs more attention and is not as comfortable - could even become molesting on longer trips. But it is a pure driver machine (similar to a Go cart) and - in my opinion - must be manually shifted to complete the joy of active driving. PDK in a 718 GTS 4.0 or a Spyder gives no sense in (of course only) my opinion. And it needs no Bose or Burmester equipment. Radio could be complete deleted - just listen to the sound of the engine. For a few hours ride the 718 GTS4.0 or the Spyder will give you a maximum of drivers pleasure on an open winding road.