[Brightcolours]

So where are those reports of shutter shock in relation to the M3, JoJu? And what would cause that shutter shock? The camera has no IBIS, the camera has an electronic 1st curtain, and no EF-M/EF-S/EF lenses are reported to be sensitive to shutter shock.
 
In case you did not understand (I am sure you did not understand): In stills photography with the current CMOS sensors, full electronic shutters result in rolling shutter effects in stills images. That is why CMOS sensor cameras use mechanical shutters. 
Implementing full electronic shutters with these sensors then has a downside, which I pointed out. It is not just bliss, and mechanical shutters do have a real purpose still. Also, the implementation of a full electronic shutter raises the noise floor and lowers the DR.
The rolling shutter is a result of a electronic 2nd curtain. The M3 has a mechanical 2nd curtain. So, no rolling shutter from the CMOS. Same with the M and M2, by the way.
You can see it in action here:
https://www.youtube.com/watch?v=CSb-bkpJipA
 
Full electronic shutters get implemented anyway, for two reasons that I know of: to prevent blur caused by the energy of the shutter, especially with IBIS cameras. And to implement silent shooting.
 
There are sensors which do read out al once, so without rolling shutter. But making those apparently is not cheap yet, hence they are only found in expensive video equipment at the moment.