I ordered the seal, received it today, and installed it this afternoon.
It indeed is a slightly different profile than the OEM seal but it seems to work just fine, and in fact it makes a slightly tighter fit when the trunk is shut as one might expect with a new uncompressed seal. The difference in this aftermarket seal is mainly an extra bulge/flap on one side which serves no purpose for our 968 application.
The overall size and the way it fits onto the trunk surround metal seem to be the same as our OEM seal, or it is so close that any differences are not detectable. I have not water tested it yet though I am not expecting any problem with that.
I would recommend this seal as a useful alternative to the very expensive OEM part.