to get zero bump steer is a hell of a feat when dealing with three different arcs, especially with two of the arcs (LCA / UCA) being vastly different due to their length(s).
I was always under the impression that the reason for raising the car when doing an alignment was because when ANY car is moving under power, drive-line torque causes the front suspension to raised slightly.....ballpark 1" . The way I see myself when driving....I'm always going thru the traps.