It seems a common and natural trend that larger formats can give finer tonal graduations in prints of the same size, with both film and electronic sensors. Larger photosites should do this (at equal ISO) due to higher signal to noise ratio; but perhaps more importantly, more pixels should should also do this, due to being able to get the same sized print at a higher PPI, producing better "dithering".
Dithering is the effect that allows even images made of solid black dots on white paper to show fine graduations of gray, because the dots are so small that what the eye sees at each location is a blurring together of numerous dots and the numerous small white spaces between them, perceived as a shade of gray depending on the density of the black dots on that part of the image. In fact, traditional black and white photographic film and prints are like this: under a microscope, you see clumps of black silver oxide on white paper with no intermediate shades of gray at all!
With film, using the same emulsion in a larger format gives final tonal graduations (one of the often stated pleasures of viewing large format prints), and that is equivalent to using a sensor with more photosites of the same design and size to get more PPI on the print.
