According to 3 separate tests, done with 2 lenses and 10 different test shots for each sensor I think the results are conclusive.
Thank you for your suggestions and advice. I am going to contact Canadian corporate and see who I can talk to there. Hopefully something comes out of that, not sure yet. Service center is Vancouver does not seem like a good place to send my camera to anymore.
I guess I will leave large Nikon Authorized Service locations as a last resort - it would be extremely upsetting and aggravating to have to pay for a repair of a manufacturer defect. And who knows if that even can be fixed at all?
In your case I wouldn't send my camera in just yet. If it's only the left sensor that's misbehaving, then maybe it's not the worst thing. On another hand - once your warranty runs out there is nothing you can do, period. And maybe Nikon hopes for people to just live with the issue because the situation can get worse? There is a reason as to why they keep quiet on the issue.