Trying to be un-biast and informative for future buyers I will try to explain the difference for those trying to decide whether it is worth it or not.
After taking the car for my first night drive since last night I think I have obtained enough information to comment. Keep in mind I am running 4,300K bulbs. If you wish to run a whiter/bluer Kelvin range then expect that to alter your visibility slightly. I found this light wasn't at all yellow but was perfect for your eyes.
Weather conditions were clear with slight fog at one point. The best way to describe the light output was think of the BRIGHTEST part of your halogen beam and foglights combined, now throw that absolutely everywhere in front of your car up to the cutoff.
Yeah, that good.
My girlfriend uttered these phrases during the drive:
"Holy s**t!" -when I turned them on.
"They're so bright!" - back road
" Wow " - multiple times during the trip... Or was that me?
Once home they firmly got the tick of approval from her (<this is a big deal and NEVER happens)
Another positive point is that because the light output doesn't change between low and high beam, just throws the light a little further you don't get that half a second of blindness after flicking from high down to low beams. This to Me is a very big plus.
Negatives (for argument sake): it is a pricey mod. Can you justify it?
If you want safety, if you want to truly see where you are going, if you want to outdo the brand new Audi's and beamers. If you want the ultimate light upgrade. I suggest you do it.
I could go on but I think it has been covered enough by others.