Depends what you shoot tbh. The Leica M range isn't for people who want to focus instantly as its an entirely manual camera. I wouldn't use the lenses on a leica M range camera either as they kinda defeat the point of having a smaller system as the lens would completely overpower it and probably block a large portion of your view finder as well, which isn't ideal by any stretch of the imagination.
If you are moving from a nikon system to a leica M system, get some practise in using just primes, as most of the leica range are primes!