Hi,
If you intend to send your M lenses to Solms for encoding, the information I have is it will take at least a couple of months. I do not have the cost, but from the discussions in other websites it is US$150 per lens. I was told Leica will change the whole mount.
Based on my experience with dealings with Solms via the local agent, the process can be slow. Last year, when I had to send my DMR to fix a loose dial, it took about two months. Fortunately, I had access to a loaner DMR from the local agent. Years ago, I sent my M3 to Solms for CLA through a friend's contact who worked in Solms and it took two months as well.
I will wait before encoding my M Lenses. The word is this might not be an issue if shooting RAW. The encoded lens will only indicate the focal length and max. aperture in the EXIF data. How this data will be used is still a mystery. There has been some discussions, this EXIF information will be used by the provided software to carry out corrections based on the focal lengths. If you are shooting jpg, this information might be used to provide in-camera corrections, but should not affect RAW files. But if you intend to shoot with the M8, RAW is the way to go.
N.S.