[Brightcolours]

Also if the pixel count is the same, smaller sensor will suffer more from diffraction.

 

It's really taking a few steps forward and few staps back all the time. It's not really like film anymore, with a well designed system, sensor size really does not matter*.

 

 

*I'm really not sure about the dynamic range and color though. My logic tells me they should also be two-steps-forward-two-steps-back but maybe they really benefit from having larger photosites. Any ideas?

The image won't suffer more diffraction with higher pixel count. Higher pixel count will just show more detailed what is going on.