The samples Mark has shown seem a bit cleaner in the shadows on the Leica, indeed. To judge DR you need to have the whole picture, that is check how highlights are exposed. I usually check images with Rawdigger before drawing any conclusion.
Not to any degree that's worth mentioning. The differences in SNR between these two cameras at ISO 3200, according to DXO, is of the order of 1.4dB in favour of Nikon, and such differences will vary according to the accuracy of the testing procedures and the variability of the quality control during the manufacture of the cameras.
Mark has presented two images as though they are shots of a high-dynamic-range scene capable of revealing differences in shadow detail. However, by overexposing the highlights (the kitchen window) he's actually presented a normal scene that's not particularly contrasty and demonstrated that the cameras are about equal regards noise in the mid-tones and lower mid-tones, at high ISO. At base ISO the results would clearly favour the Nikon.
If anyone wishes to compare shadow noise, particularly deep shadow noise, then I would advise him to compare images that have been properly exposed for the highlights such as a bright scene out of a window.
C'mon guys! Wake up! This is an April Fools' joke posted a bit late.