I\'d guess it also depends on the sensor technology. If the photosites have relatively more noise at lower light levels, then a lower resolution may cause more noise even overall,per-image. If the noise is proportional (or almost), over a large range, then the per-image noise doesn\'t change. Another possibility, depending on the sensor technology, is that in dark shadow areas, or ultra low-light, there will be more noise (even after downscaling), but otherwise, it will be similar (after downscaling). That would need to be tested, and it seems that currently, this question is not tested very much.
