Mike, have you modified your NSX? A lot of warranties don't cover modified cars or exclude a lot of things based upon the mods.
If so, I think you should stay away from extended warranties for sure.
If your car is stock, I still think you'd be better off not buying an extended warranty unless you feel you have a lemon, or your driving habits would cause undue wear and tear on the car.
I think the money saved could be used for future repairs.