Yeah I got one. Primary lenses used are Leica 28/2 ASPH, 50/1.4 ASPH, and 90/4 Macro. Also have a ZM 50/1.5, 21/4.5, and a few other lenses I don't shoot much (Nikkor 50/1.4, CV 28/3.5, etc).
It's great. The M10M has no issues with difficult lens designs like the Zeiss ZM 21/4.5 - no significant smearing! All the character from these lenses shines through just fine, though I'll be honest I've not tried the Nikkor 50/1.4 much. I did shoot that a few times on the M9M that I rented many years ago and it was nice, and the few M10M images I shot with it seem fine. As Doug stated above, sharpness comes from a combination of the sensor/film and the lens. A higher resolution sensor can only make a given lens look sharper than it does on a lower resolution sensor (barring smearing, etc.)
I have no issues getting sharp (enough) images handheld wide open. Post processing hasn't been too difficult either. As everyone knows, since it is monochome, if a highlight is blown, there is only one channel so there is no recovery from other channels. Thus I often shoot it at -0.7 exposure compensation. It's easier to get (small) blown out highlights with a wide lens as they get 'averaged' out easier by the simple Leica exposure metering scheme.
My only complaint, and this is true with all digital cameras, is that when light is plentiful, I personally find it easier to expose with negative film. Set the exposure for the shadows you want, and fire away. Highlights take care of themselves. Digital is obviously a little more finicky (I know, expose for the highlights), and the M10M isn't really any different. On the other hand, the ISO capability is amazing which really opens up options when light gets poor.
Back to the resolution - I say don't worry about it. If you like the resolution you get from 35mm film, you'll get that and more. No need to upgrade. I also shoot a Sony A7rII (also 42 MP) and find the same thing. I just shoot it like any other Leica with the same lenses and the files look great. I don't obsessively zoom into 100% and examine sharpness everywhere, just like I don't with my film images. *Maybe* sometimes my focus is a millimeter off from where I want, but when I get done processing and view the image at the size I normally would, you can't tell - adding a little grain in Camera Raw goes a long way as does downsizing the image a little bit (or not viewing at 100%). Short version - yeah there are a few photos that might not be optimally sharp, but were all my film photos sharp?