I'm afraid of the complex SL menu and focus peaking and so, I'd go for an M10.
OTL,
First came the Leica "S," then came the SL, then came the M10.
Pretty much the same camera, but packaged differently.
The "S" and SL share the same Leica menu layouts. The M10 is basically more of the same.
Be aware that when using non rangefinder lenses on a M10 you can use live view or focus peaking for focusing. So your argument is only valid if you want to live only in the realm of rangefinder lenses and you choose never to use liveview or focus peaking ever.
The SL has a zoom that is joystick movable, so I primarily use magnification to nail focus optically. Of course this is more suited for normal and longer lenses, but workd for wides as well. The SL is more like a SLR in this manner.
Know that on the newer Leica digitals you can remove features and dumb down the camera into a very basic camera. Also you can make your own custom menu. In my case I pretty much made my SL a simple and basic camera.
So with my SL I have autofocus capability, but the AF lenses are not small or compact. I have grown fond of the electronic VF'er, I also love how I can select my metering (I use spot metering, and combine that with singl point autofocus)
When I mount my 28 Cron-M the camera is basically utilized as if a fully manual film camera. No complexity at all.
I think you are mistaken that the SL is more complex than the M10. Pretty much they are the same camera just packaged differently: one is more SLR like; the other a rangefinder that is of course more compact, smaller and lighter in weight.
Lastly I have a friend who owns a SL and bought a M10. He also says that the cameras are remarkably similar, and that he wished he did not buy the M10.
There is a Leica three lens "S" kit in a Pelican Case that gets loaned out. My friend "Mike The Skinny Hipster" knocked on a door on the Lower Eastside and was handed this kit on loan that went down like a 1970's drug deal.
When Mike got the kit home he called me to come up, and know that Mike lives in the apartment right above mine. The same layout as my SL I would learn, pretty much all of the same.
If your have the most recent issues of Leica S magazine or LFI the work from Mike using this "S" kit is published in these two issues.
Cal