Nice test! I'd like to see the results.
But unfortunately the outcome surely depends on the algorithm of the in-camera processing.
My suggestion in any case would be: Always shoot in full resolution and apply some high-quality de-noiser in software afterwards if you think that's necessary. In that case you have more freedom, because lost resolution can never be brought back to the original shot
P.S.: keep in mind that setting the cam to lower resolution will not really decrease the noise of a single optical cell
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