MMD, this is my first Porsche so my comments might not be as useful as other members. The car doesn't feel like a go cart at slow speeds, IMO the steering feels spot on, turn in and fast cruising are just as they should be. You'll forget the car has variable steering within the first 5 minutes (if you noticed any difference in the first place). So don't worry or be concerned, everything is as it should be.
I drove about 250 miles yesterday and the car was very stable and easy to drive at speed, some of my driving involved fast lanes with fast corners, I didn't notice any difference in the steering during the whole day, it's that good...