Marc,
To my eyes the Nikkor 24-120 shot, comparing the same areas in both crops side by side in Photoshop, appears to give an impression of finer texture, little hairs sticking out all over the place. The Leica crop seems over all smoother. On the other hand, at 200% enlargement, the Nikkor shot gives the impression of having had more sharpening. Have you applied different levels of sharpening to these images?
Am I the only one that finds this series of posts quite amusing?

Is this the antithesis of 'Real world photography'. My wife thinks I spend too much time looking at LL anyway - and if she reads these posts she will think I'm not using my time profitably!
Jim