[thxbb12]

For MFT sensors at 16 MP and 20 MP these sensor diffraction limits are F/12 and F/11 respectively, but to get the most out of this you generally need to stop down  a full aperture less, so F/9 and F/11.

 

This is incorrect.

As we can see from the charts here at PZ and pretty much everywhere else, diffraction hits well before these aperture values.

A good example is the best MFT lens tested here in the zone, the Oly 75mm f1.8: http://www.opticallimits.com/m43/830-oly75f18?start=1

From f5.6 onwards, the resolution is hit by diffraction already.

Keep in mind that the higher the sensor resolution, the sooner it will be hit by diffraction.