OF course the LTM adapters also work fine on any Leica Copy, including Canon, Nicca, and the new Voigtlander. The LTM adapters can also be used on your M, with the LTM to M adapter. There is no rangefinder coupling, but TTL metering is maintained. Of course you can add a bayonet adapter to the Nikon - Screw mount adapter and use that on your M too. To increase your system's versatility, reduce investment.
Wide angles are very usable without the rangefinder coupling due to their great depth of field.
Just use scale focusing on the focusing mount, and you will seldom find yourself out of focus. In use the adapter snaps on with precision, though I do wish the spring on the Nikon release was a bit stronger. Shown is the 35-200 Nikkor zoom on the M6. Leica never made a 200 to attach directly to its RF bodies, but you can with this adapter. The Pentax 42mm adapters have a ridge inside the adapter which stops down the lens, making the adapter usable on any make 42mm screw mount lens.