+1 on what Max said, for simplicity and peace of mind reasons.
Fitment: you could certainly get away with a nice set of wheels if you can ensure that the adapters you add to the existing assembly are spec'ed. Meaning by that; concentricity and parallelism tolerances, lightweight but durable material and balancing. Reason for that is to "minimize" vibrations as much as you can (you won't be able to eliminate it completely, sadly). So... you can't cheap on that part.
Personal view on "adapters": if the car is driven at e.g. weekends only, 25~45mph, rural roads, etc, then I don't see a major problem. if however you fancy long highways, twisties and occasional fast & furious then that might not be such a good idea.
Lastly, only a licensed engineer (ideally working for Porsche and with knowledge of the 986 wheel assemblies) can answer the question about the reliability & durability. I doubt any forum member can or will answer that question for you
Hope this helps, probably not (sorry)