I'm not sure if I got your problem.
Usually DAVID chooses the best mode (vertical, horizontal, or both) after calibration and you don't need to change it.
The vertical mode has to be used when camera and projector are placed on an vertical axis (i.e. on top of each other), whereas the horizontal mode has to be used when camera and projector are placed on a horizontal axis (i.e. side by side, like in the SLS-1). If projector and camera are mounted on an diagonal axis, "both" is the best mode.
In other words: If you have a vertical angle of 21 degree and a horizontal angle of 0.9 degree you must use the "vertical" mode (or "both). The horizontal mode is wrong and would produce very noisy scans. So regrading your example images: everything works as expected.