Thanks to this thread, the taillight fit was one thing I was looking for when I took delivery. My driver's side rear was snug up against the panel at the middle top, with plenty of clearance everywhere else. I took it to the dealer. They weren't familiar with the problem, but agreed to take a look at. I emailed them the photos just for educational value, which probably helped remove some initial skepticism.
They shimmed it out with a washer or two, same conclusion as we've seen from others. Looks fine now -- not absolutely perfectly even gap top and bottom, but plenty of clearance all around for a business card. Even got a free loaner. Great service.
An ounce of prevention is worth a pound of cure.