I have 2 different types of LEDs on my 2 wheels. One (red) is the conventional commodity 20 degree LEDs and the other (blue) are wide angle devices. Since I can watch them side by side I've noticed something interesting about the regular 20 degree LEDs. As you ride by you see the display but as the wheel passes directly in front, and the viewer falls in the narrow beam of the LEDs, you see glare, like looking directly into a flashlight. You can see the effect in the photos on this web site where the color saturation is different in the images for different parts of the wheel. The washed out colors are when the LEDs were pointed directly into the camera lens. You see the effect also as the circular striping caused by LEDs being mounted at slightly different angles but producing greatly varying intensities from a given angle.
In contrast the wide angle devices give the same color quality from viewable angles and no noticable striping. This is at the sacrifice of some bright ambient light visibility for direct on viewing.
See image below for time lapse exposure of 4 spokePOV (2 red, 2 blue) showing glare on red when it is directly broadside.