I regularly use Canon 1D Mark IV and 1D Mark IIN camera bodies. I also have a Canon G-15. I always shoot Canon RAW. I find the image quality from the M to be substantially superior to the G-15.
Excellent image quality for both still and video images. Many manual overrides, when desired, for the extensive auto functions and modes. Photo RAW; 2:3 format that is consistent with Canon's pro cameras. With 22mm lens it's a compact, light camera
There is no effective rapid-fire of images as compared to G series or pro-sumer Canon camera bodies