But Bill, I think white bulbs will be fine, although I do love how rich the amber light is in my front signals. Without a luminosity/color gauge to quantify, I think it's mostly academic though.
Hell, clear incandescents worked fine until some idiot started a thread about LEDs!
Here is the problem. The light from the White LEDs is not the same as the white light from an incandescent. An LED-- whether it be yellow, red, or green-- puts put almost pure light of that color. Look at them as sloppy lasers. A White LED uses smoke and mirrors. It puts out Red, Green and Blue light and mixes in specific proportions to create light that is perceived as white to the eyes.