This year I replaced my M240 with the Leica SL. Most of the time I use the Vario 24-90mm lens which is just great. For low light and bokeh I use the Summilux M 35mm FLE, which is also a great match. At my last holiday I took my Noctilux to see how it works on the Leica SL. With the Leica SL the Noctilux is easy to use because of the great EVF. I can focus easily even without focus peaking. With the fast shutter of the Leica SL I can use the Noctilux without a ND-Filter which is good.
The colors are a bit cold for my eyes. On the M the colors are more vibrant. Anyways, the overall look is typical Noctilux which is great. I used the Noctilux just for a few shots because the Vario is more flexible and the quality is just amazing. The main reason why I use the Noctilux is the special look wide open. It can create images which are unique.
You can find a complete review of the Noctilux here.
As you can see, the Leica M produces much warmer colors and a bit more vignetting. I prefer the Leica SL as the images look more natural. Of course I could correct the white-balance to let the M240 images look like the SL-images. But I have to do that every time for each picture. Sometimes the M240 toning is attractive even if it is not neutral. At the end it’s a matter of taste.