Originally posted by Dericali I would advocate not using focus peaking for critical focus... Use live view and zoom in and use your eye.
I would not generalize this, it depends on your subject: I use it and it helps me to correctly place
the plane of focus. It's one thing to focus on a point, but in macro shots it helps me to adjust the angle at which I'm shooting, so that the thin in-focus range e.g. covers the intended body parts on an insect. Being able to change color, or even select to use the complementary color for outlining, would be a huge plus for me. With a sense of DoF, I definitely use it for critical focusing within some tenth of a millimeter in 1:1 handheld shots successfully - often not instead of, but in conjunction with magnified live view.