Nikon glass has come a long way from 1960. Still I use some single coated 24,35,50,105 from then and they seem to make nice pics on a D700 & D3.
I have new Nikkor lenses like the 35 1.8 and 60 2.8N. They are more Leica like. They were bought for D7000 use and are but a week old. I did a few shots on the D3 with the 60, and I must say it is a gem.
Leica has become more and more increased micro contrast so they render very small detail well, almost too well at times. For landscape work they are wonderful. A lady over 18, well not so good. Learn photoshop well. An old man with a beard and pipe, just the ticket.
I think you really need to decide if you want a RF or reflex camera. IF YOU PUT THE BEST NIKKORS on their digital body, you will be pleased. One of the kit Nikkors for $125 is another matter. They are ok at F5.6, close up, wide apertures they are just ok.
I can recommend my D7000, 35 1.8 60 2.8 N as best in class.
I should mention, distortion, Nikon seems not to care specially with zooms. You do not see that with Leica lenses.
If you like to shoot wide, M9 has the red edge problem not addressed yet. M8 has the IR problem which shows in some pictures. Unless you are a wedding or fashion guy, this is a non problem in my opinion. Just make a selection of the purple cloth and desaturate it. No big deal unless you have a 300 pix wedding to repair. I would put an IR filter over the flash.
Leica excells at sharpness mostly because of a lack of AA blur filter over the sensor. The penalty is moire sometimes. Photoshop again. Happens when fine detail matches the pixel repeat pattern. Again, fashion, knit cloths, anything with repeating lines are all potential problems.
Good Nikkors are becoming comparable with Leica lenses. You will need pretty large prints to see a difference.