I have been using the 007 some months now and still have my D810 but only use it for wildlife. I sold all my ZF lenses (21/25/35/100) as I think the Leica alternatives are better. For me also the "shooting envelope" has been a main factor to go with Leica. Here are some preliminary conclusions which maybe of interest:
- Side by side the Nikon is still faster and quieter but not by a far extend. For a MF, the Leica is very responsive and sufficiently close to the D810. The new processor is up to the task. The Leica is heavier, but I compensated this with less lenses. There is no Silent Wave motor but the noises the lenses produce are not that annoying as I thought.
- Shutter vibration has been no issue, very soft, indeed it is like closing a Mercedes door. The viewfinder is much better than the Nikon. I also prefer the simplistic user interface of the Leica with programable user scenarios which I use all the time (Nikon does not have that).
- The AF has some issues, at least for me, the focus point selects sometimes another point that it should, resulting in back or front focus issues. Nothing very consistent, but you better check your photos.
- The Nikon/Sony sensor is clearly better in terms of DR and malleability. I was worried about that, but in practice it has not been a big issue with my landscape photography.
- I was thinking to go the Otus line, but at the end did not go this way, mainly because of the limited lens selection (no 19/21 or 24/25) and no AF. With wide angles lack of AF is ok, but not so much for standard and tele lenses. I would say the Leica lenses are in the same league as the Otuses, as far as I could test it. Nice thing of Leica S lenses is that you can use them very well with MF. It is not the same buttery feeling as Otuses or ZF, but still very good.
- I made some side by side comparisons when I still had my Zeiss ZF2 wide angles. The Leicas - in my opinion - are clearly better in terms of out of focus rendering, tonal transitions, micro contrast. The borders are very, very good. The lenses have a very distinct character, compared to Leica M or Zeiss, and I like it. I think that the lenses can do much more than 37 MP, but sure the fat pixels help to augment the acuity, this is visible at 100% comparing with the Nikon D810.
- I use Lightroom and with the Nikon files it is a constant fight, as I do not like the Adobe handling of the NEF files. This has gone with the Leica.The DNG files look very good out of the box and it is easy to tweak them with some color profiling.
Summary: It was a heavy "investment" for me as an amateur, but I am a happy camper and have no plans to go back.