The MM is certainly special in the right hands. For me it's an interesting product.. it's too expensive to buy since I don't really do bw, but on the other hand would be interesting to try.
I've also thought about getting a film Leica and trying bw that way. Would be a lot cheaper, but I'm also a lazy git so fiddling about with developing my own films etc might turn out too much for me.
I guess I'll just try jpeg+raw in the M240 and set the jpeg for bw. That should get me started
About the Nikon, I think it was already published - a Nikon D810. They say it's the Nikon D800 on steroids with many improvements and no AA filter at all.