Here's a few quick notes about each option you may find interesting:
Amber:
- Pro: Great for low visibility situations. Think dusty off-road situations and foggy weather. Amber is a "warm-white" compared to the Yellow Lens and will block more blue light from passing through. Blue light is reflected by the fog back in your eyes. Blocking that blue light spectrum will help you see much better through the fog.
- Con: If you're adding a lens on a large light like the D3, D4 or D7 everything will be "painted" that color at night. It's very close to the color of Deer fur and will make it more difficult to spot critters as your color recognition will take a hit.
- Con: As the light needs to pass through the colored lens you will lose approximately 25% of the light output/distance.
Selective Yellow:
- Pro: Ideal for sunny daytime riding, as it has more of a "dazzling" effect when looked at. It appears visually brighter as the Yellow lens is less restrictive and doesn't block as much light down range. If you like the look of colored lenses but want to minimize light loss, the Yellow is the way to roll. Perfect for daytime conspicuity.
- Con: Similar to the Amber in that you lose some of the color recognition, though it is slightly less impacted as it is closer to pure White.
- Con: As the light needs to pass through the colored lens you will lose approximately 10% of the light output/distance.