The ‘Silent Shutter’ mode is (electronic front & rear shutters) is very useful as it really does reduce a lot of sensor vibration (not that the a7R’s mechanical shutters are very heavy – certainly nothing like the shutters let alone mirror on an e.g. D7100).
However, despite Sony’s claims about the amazing speed of the electronic shutter, it’s really rather slow. Even slightly moving subjects – e.g. a flower in a very light breeze – will show a pronounced rolling shutter effect much of the time. In a nutshell, ‘Silent Shutter’ mode is really only trustworthy for stationary subjects & scenes.
Though sometimes the effect is quite amusing. For example: