Thanks, I did see some distortion with hummingbirds today. So it will be dependent on the speed of what you shoot. I used the 20fps most of the day without issue.
How it fills the frame vertically is very important. Something 20% the height of the frame is going to have the shutter roll through it 5x faster than something as high as the frame. Crop mode is going to have the shutter roll through it 1.6x as fast as FF mode. This is one unusual situation in which keeping the subject small in the frame can be beneficial, if the subject moves very quickly.