I went into a deep dive into the portraits I took this weekend. In some of them, I did notice evidence of shutter shock in the images taken around 1/60 to 1/80 shutter speed range. Nothing that ruined any shots, but it is there. Seems to have gone away once I hit 1/100.
I think that I will investigate using EFCS in those situations where I know I will be shooting with that shutter speed for any length of time. Although, since ISO is not really a concern with me on this camera, I might just shoot manual with auto ISO and force the shutter speed to stay above 1/100.