If you plan on gaming with the Vizio M Series, start off with either Game or Computer modes before making adjustments. Otherwise the input lag will be very high (133 ms vs 41.5 ms). You can't use the motion interpolation feature in these modes, though.
Turn off 'Auto Brightness Control' to prevent the TV from automatically adjusting the brightness to the ambient light of your room. The 'Backlight' setting will then become a real adjustment for the luminosity.
As usual, we recommend turning off every option. See the Q&A section of our review to see why we don't recommend using the feature called 'Active LED Zones' or 'Motion Blur Reduction'. If you plan on watching SD or 720p content, turn on the noise reduction features to compensate a little bit for the low quality media.
The 2 point gray scale calibration was close; only small changes were made.