Curious that people will pay thousands for a Leica that only does black and white when all anyone has to do is click a button for black and white. I’m guessing there’s something magical about completely removing the rgb pixels, but I don’t get it.
Leica is a luxury brand that sells for more than they could get even if they were a monopoly. So that particular factor alone makes dollar value unimportant.
However, a monochrome sensor has about a stop or so greater quantum efficiency, allowing the same dynamic range of what would be the green pixels at the proportionally higher base ISO, and what would have been the red and blue pixels—or half the sensor—get several stops more exposure, leading to less overall noise.
Also, color aliasing is eliminated, giving cleaner fine details. Blurring of the chroma channels is a standard technique in raw processing, and elimination of this step improves resolution even more.
It’s arguable whether this extra dynamic range and resolution is actually needed for most photographic purposes. I can think of some.
I wouldn’t purchase a Leica even if I could afford it, and I’d only rent one if my client expects something special and is willing to pay extra for it.