Thanks for the excellent review (and pics).
Before reading it, I wasn't aware that the M10 isn't the better camera than the 240 in every aspect. Size and weight are important, but not everything. Functional handling is everything for a Leica (or a RF, or a camera in general?) If so, fast ISO setting is more important than doing it with a separate, fix dial, which looks excellent in the first view.
Very often I use the +/- AE setting dial at FUJI's or other cameras, usually at -1/3. So I use this dial far more than the shutter speed dial (which stays mostly on AE setting). I tend to change my long-held oppinion regarding the need of a shutter speed dial (even most of my cameras have it).
Regarding the special question "M10 or 240?" this review is particularly helpfull, and I tend to share Huss' rating about the built-in horizon levelling tool of the 240. I'm so used to it, I even can't imagine a high level camera comes out not having this feature. With most pictures on monitors, a slant horizon is far more unpleasent than it was in the era of analogue prints. And it's quite hard to get it by hand without help.