Hi kshapero. I think the reason the electronic shutter option is off by default is to prevent horizontal distortions on moving subjects. Electronic shutters generally scan from top to the bottom of the sensor, meaning that the top of the picture represents a different point in time than the bottom of the picture does. This can produce weird
"jello effects." A mechanical leaf shutter prevents this by turning the entire sensor on, then opening and closing from the center.
But the electronic shutter has the advantage of faster maximum speed, which allows some more depth of field control because you can open the aperture a couple extra stops in bright light. Also an electronic shutter doesn't wear mechanically like a leaf shutter does, although I've never heard of an MX-1's leaf shutter wearing out.