But there's still only 6mp worth of genuine image detail in there regardless.

Actually, I would say there are 2mp worth of resolution. You see, in almost EVERY digital camera, each pixel collects one primary color of light which is then combined in order to create a full color image. Hence, even though the camera is collecting 6mp worth of light, it takes three of those pixels to make one pixel in the final image.

The only camera I know of so far that captures RGB color on EVERY pixel is a Sigma. Pretty nice camera, actually.