Raid, I would recommend buying the Leica brand adapter. I have a handful of off-brand adapters for my SL and the quality is lacking in comparison. Also, the electronic functions are non-existent with off-brand adapters.
If you're on the fence about buying an SL, I can highly recommend buying one. I got mine a few months ago after sending in an M9 for sensor repair. It was a difficult transition, I've not focused an SLR style camera in decades, but it has been worth it. I am very happy with the prints I've made from this camera. The functions of the camera become second nature pretty quickly. The size was a big turn-off to me at first, but I've adapted to it.
For me the biggest benefit of this camera has been being able to use just about any lens without dealing with rangefinder coupling. I have adapters for Nikon, Olympus and Canon lenses and they work great. The 7Artisan lenses are particularly easy to use on the SL as you don't have to spend a Saturday evening adjusting the focus!
In short, if you're used to RFs, there is a learning curve with the SL, but it is not as daunting as I thought it would be. My M9 still gets used, but it is definitely being used a lot less these days.