Randy,
Guess very few like visual light realism in this game now that it is possible. That is how dots looked projected on glass using the technology of the time. I have a completed MKII for the British gunsight that over saturates with an orange nimbus just like the photos when the slider is to the right.
Optical gunsights needed a rheostat to control the glair at full bright that created the nimbus effect and allow changes for the time of day or night. The projected reticles were not the crisp 2D images we have come to depend on in our cartoon game. You get closest to that by dimming the alpha but, have the same real world problem of the reticle fading away. So your description of the slider sweet spot about center is accurate.
You didn't like seeing that realistic orange light in your reflector plate....