The premium upgrade only gives you leather and a shaker 500. Other than a prestigous sounding name (witch is why it sells as well as it does) all you're getting is a savings of $180.
Yes, the insurance trick worked back in the 80's. Especially the early 80's, but by the end of the decade when the LX 5.0 had gotten so popular, they had figured out that model was just as fast as te GT and was actually more dangerous when you consider how much lighter the back end of the LX coupe was compared to the hatchback GT.
As for a stripped down V6 looking "LX" model (call it something else though) with the entire GT drivetrain, HELL YES!! Except for the front fascia, and the wheels the V6 looks better than the GT anyway.