If you haven't used this with macro shots or if you don't even have a 40D or Mark III, any arguments you might make about live view "being useless" is therefore about as useless.
Not only during macros is this useful. If you have your camera on a tripod such that you have the height where you want it perpendicular to the portrait area (which for those of us vertically challenged probably means you might have to have the camera in an awkward height to use the viewfinder well), you can use live view to compose your shot, assuming you already have the focus locked, and your aperture high to get a deep DOF. As you have folks shuffling in and out of the "photo zone", all you have to do is enable live view, compose the shot, then take it. Works great.