The Porter Built arms have some corrected geometries specific for lowering the vehicle, I am not positive if the length of the upper has increased but the idea is to lower the vehicle to a desired ride height via the dropped spindle and the dropped cross member so that the control arms are basically the same position as stock. This way there is adequate swing both up and down before it starts affecting steering and alignment. If I can get it as low as I want with the addition of a drop member then the articulation of the upper control arm will not start drawing in the upper ball joint as it travels through its arc by the time it hits the bumps.
Watch the attached video, Nate has his product on Nacho. Notice how when he airs down to extremely low his spindles stay mostly vertical. Since it is a rotating member there is always going to be some inward movement of the spindles but getting the geometry correct helps the ride quality.
https://www.youtube.com/watch?v=9bwqlwiZOyw