I'm getting my NEX's NPP set pretty well. I've almost got the buzz saw changed into a complete circle. But I noticed something about my camera and maybe about all NEX's.
If you use the grid lines on the LCD to center the camera on the South pole, you'll be way off. I had the center of the NN3 knob right in the center of the grid and the buzz saw test showed that I was nearly a cm off. After multiple test panos, I eventually moved the vertical arm from 5.2cm to 4.5 cm. Hard to believe the grid lines are that far off.
It might be that the camera bottom is not perfectly parallel with the optical axis. I don't know. Maybe there's something else happening that I haven't figured out yet.