Leica monochrome is one of my dream cameras. Even the ancient Kodak 760m was my dream camera.
I was simply attracted to the camera with the sensor of the non-Bayer type which is free from the artifact associated with the demosaic algorithm. I was about to go for a FOVEON sensor camera made by Sigma, as it can function as poorman's (not rich, not young) Monochrome.
That said, Leica's characteristic rendition is largely thanks to their lenses and the sensor design dedicated for them, color or monochrome. So, you should have to invest on the lenses as well as the camera.