All this talk about noise reduction, what is this? Is it only about reducing noise in camera JPEGs? To me that is next to meaningless, I shoot RAW only and rely on noise reduction in RAW development software. However, read noise reduction at low ISO would be welcome to me. But is there much you can do at high ISO any longer? Read noise at high ISO seems low to me already on the newest sensors. Isn't nearly all noise in typical high ISO pictures just unavoidable photon shot noise?
And as far as I've understood there's no law of physics that says that larger pixels will lead to less noise, so you could combine high megapixel count with low noise, historically it has indeed been tough, but it seems to me that with newer sensors the problem has become smaller and smaller. A higher resolution picture will of course look more noisy at 100% crop due to more photon shot noise per pixel, but when averaged/binned it's the same as for larger pixels. If you're only going to shoot high ISO I guess it makes little sense to have high megapixel count since you'd want to average/bin them anyway for noise reduction. However, I guess for many of us that do 90% of the photos at minimum ISO, a large pixel count is welcome, resolution is indeed a key aspect of image quality.
One aspect that I'm a bit unsure of is the quantum efficiency, perhaps there's stuff to do in that part? QE = how many of the incoming photons that actually become registered by the sensor. If that can be significantly increased, there will be a true improvement for low light shooting. I've heard that it's around 40% of today's sensors, not sure if it's correct though. If it is, there's ~1 stop improvement to do there.