(Megapixels) War...what is it good for....

[Fast Glass]

Another thing is, more resolution technically doesn't increase noise per say, beyond the limits of the each pixel well's ability to collect light efficiently of course. It's the sensor size that is giving you more "Light gathering" ability. The smaller pixels allow you to magnify the already existing noise, but it's not increasing noise of the whole image. If you were to print the image the higher resolution image will be overall better than the lower res one. Although I'm sure there is a point if diminishing return because once your hitting 100,000 ISO I don't think your gonna see much difference when the whole thing is a mess of noise anyway!

The more pixels you have it loses a small amount of efficiency. Gapless micro lenses help a lot along with other modern advances in sensor technology but there is still some loss. So in that sense smaller pixels are adding noise. But usually Cannon offers little tweaks to the sensor to try and midigate that difference with modern high res sensors.