I added mine purely to be seen by otherwise oblivious drivers! The amber lamps plus my headlight modulator/brake light flasher combo ($85, click HERE
for the website) ensures that those around me notice me 99% of the time. I even had a weak minded driver pull over to the shoulder on GA 400 this week she was so fearful of the Mighty Road Star!!
Night vision only increases marginally from my point of view with passing lamps, but I'm much more visible at night.