WOW! A thread that goes all the way back to 2003. Now that's staying power!
I'll throw in my 2 cents, but I'm coming from a whole different direction. I don't ride my (adventure-style) motorcycle at night very much because the OEM lighting is so poor that it's just plain dangerous. Can't see the road!
But I did buy a set of Sylvania Silverstars (H4) to improve the conspicuity of my bike during daylight hours. A yellow H4 halogen headlight does not get you noticed by car drivers. The Silverstars (at a claimed 4000K) make the bike look a tad more noticeable because the headlight color sets you apart a little bit from the crowd. But really, not much. I ended up replacing them.
I'm currently using a set of cheap blue-tinted H4 bulbs that all the "experts" say are junk. Not for me! My blue-tinted "junk" bulbs ($30/pair on ebay) are an excellent color match for my 6000K HID off-road lights and, during the day, they make my bike sparkle like a little diamond! I've actually observed this myself when I loaned the bike to a buddy while I drove my car. In the rearview mirror, my bike really stood out from the line of cars behind me even when my buddy was 3 or 4 cars back. I'm convinced that a 6000K blue-tinted halogen bulb, even if it's only the standard 55w/60w, improves daytime conspicuity and therefore improves my chances of surviving another day.
