Cool Thread! Never seen the all-rubber tail before. Did Porsche also own a rubber company in the 70's and 80's??
----- a joke. I personally love the look and texture of the rubber.
^^The tail you show there is a Tea-Tray spoiler. But looking through the vents in the first photo it appears that it is just the tail bolted to a Carrera/SC non-spoiler lid. I don't know if this is what the factory did, if it is factory you are looking for.
Given the recent article in
Excellence about the early M491 Carrera that was 'too early' to be true, along with the mystery that seems to characterize this production of this era, its probably fair to say that many cars could have slipped under the radar with a different tail than what they should have.
That said, the choice should really come down to what you think looks best on your car!