Actually amber is used for many different purposes. Roadside warning flasher on barrels for example. Tow trucks, work vehicles..etc...I think of it as a "universal warning" indicator. I use an amber high powered torch as my daytime rear warning light. I figured if it's different it draws attention, at least that's my theory. I don't use it all the time though, only when I have to ride day on dangerous roads. At sunset and night I use only red rear lamps. I thought about buying the DiNotte amber version of the Quad red but cost too much money and likely I wouldn't use it much anyway.

I mentioned this before on forum but will do it again; I'm seeing more people using "white flashing lights" on the rear of their bikes. I hate to say this but it works. It draws attention. Yesterday I had to work and drive through Washington DC. I came across a guy riding his bike in the early evening ( still daylight ) and noticed that he was using a Knog ( 4 led ) "white" flasher on back of his seat post. It was in heavy traffic with cars juking all over the place. First he'd pass me and then I'd pass him. This happened several times. The Knog was very bright. That said it wasn't so bright that I found it irritating, just very noticeable. When I would get stopped by a light he would ride through the light and I would still be able to see him from two-three blocks away. Different...but if it keeps him from getting hit from behind it has served it's purpose. Now he did have the dinkiest little red light on the helmet I ever saw. It was so weak it was almost useless.