Your eyes see best with the whiter light of higher temps as already pointed out.
I have read before that amber lighting was originally intended for racing as it was easier to actually see the vehicle coming at you. They were not intended to increase the visibility of the individual driving the vehicle with them. It is argued that the amber lighting will help you in poor weather but there really is no proof that this is the case. Just think how white light is even hard to see on wet roads, why would something not as bright or white be any easier?
I have run amber bulbs in previous vehicles (fog lights only) and while they look cool and are certainly different, I cannot truly say I gained anything performance wise. I definitely would not recommend them in the low beam though unless for show.