I love the light output of my 6000k. The 4300 and 5000k kits will probably produce better results as far as light output but 6000k is a good compromise between "appearance" and performance. I notice dramatically increased performance over my stock halogen bulbs. Unfortunately I cannot comment on the defined line you see when your alignment hasn't been screwed up. I noticed it when I first got the car but I had since messed up my alignment and had to realign them. While I have gotten them pretty close to where they were, they are not perfect. Still, I feel that the performance of my HIDs are superior in every aspect and situation that I have encountered over my halogen bulbs...that includes rain. I have not had the opportunity to use them in snowy conditions but I will most likely drive my '90 Accord beater on those such days anyhow.
I used to get flashed by people when I originally installed my HIDs because I had one aimed too high. Now that I have realigned them, I no longer get flashed and my field of vision is excellent.
The installation is as easy as changing your regular bulbs (which is a PITA)....the only addition is really figuring out how to mount the ballasts. Currently I am unhappy with my mounting positions and will fix that when I install my turbo kit. If you aren't worried too much about underhood appearance, just find a place as far away from the exhaust manifold as possible and as dry as possible. The kit should come with two sided tape but it won't last forever so look at strapping the ballasts down somewhere or screwing them in somewhere. The wiring is really easy because it plugs right into your stock harness. Another cool aspect is that with the ballast, when you flip your high beams on, the low beams stay on for the extra side visibility.
As far as the line you are talking about in the reflector, I believe you could be referring to something you will normally only see through projector beam headlamps. Even the stock reflector type HIDs don't have this line that I think you are referring to. It is just a light blue tint to your light ouput but it is very white on the ground.
Hope this helps.
Edit: Here are some pics. My camera is a 6yr old 4MP camera so the images aren't great and well I'm no photographer either. These pics are not on even ground and not lined up with anything but hey I live in an apartment and this is my handy dandy carport. They kinda give you an idea of color though and the illumination pics are without and with flash.
