After having HIDs (factory on my 328) I can't go back. Even bright bulbs like SS Ultras seem dim. I used the factory bulbs for a long time, but when I got my M-Tech 2 front bumper and projector foglights I decided to go for HID fogs. I went with 5000K bulbs for both, as there is no difference in visibility to me but I do like the look a bit better, especially since they match the 5000K 200LED "Angel Eyes" I installed at the same time (LED eyes were a big visual improvement from CCFL). I have since replaced the headlight cover with completely clear glass ("Euro") with clear Lamin-X and new, ultra-slim/low profile ballasts that are about 20% more powerful as well as much better wiring. My low beams are fantastic, the cutoff is so sharp you could use it to trace a line with a pencil from 100ft away, the light is incredibly even, and I feel absolutely safe. With the lows and fogs on together, the light pattern is significantly wider for a good distance then cuts off into the main beam's path. I am considering getting a set of yellow HID bulbs for the fogs for use in early spring/late fall when there is a much greater chance of rain, and using the 5kK ones the rest of the time (the car is stored in a climate controlled garage in winter).
Alternately, I could just get a second set of glass lenses for the fog lights and put yellow Lamin-X over them. I don't feel it would work as well though.
I use high wattage SS Ultras (the European ones) in my high beams which are also DRLs, as they perfectly match the 5kK HIDs and Angel Eyes. I upgraded the wiring to a thicker gauge and have had zero issues with the higher power draw, only benefits (stronger DRLs, stronger highs, etc), and I doubt they are going to melt glass covers.
I also have my car wired so that I can use the fogs, highs, and lows all at once as I do enough driving out in backroads of nowhere that it is very beneficial. Typically, though, I just use my lows, fogs, and the always-on Angel Eyes. During bad daytime weather, it is nice to be able to have the Angel Eyes and DRLs on with fogs and no lows/highs: it cuts under the rain, does not produce any glare for other drivers, and it makes my car far more noticeable (I do not want to get hit).
In the end, I would never buy another car without HIDs. They are such a low cost option relative to the immense benefits. However, you will never see me with purple or strong blue tints from my lights... A friend has 10,000K HIDs in his Audi and they are good for nothing but show: the light output is hardly better than Silverstars. Better than the 18,000K bulbs another acquaintence had in their Range Rover Sport Supercharged, those were like trying to drive with a neon bar sign lighting the road. Especially as he was putting out over 525hp (S/C belt, pulleys, intake, headers, exhaust, remap/tune, and tranny software flash). Scary. He has since replaced with 5500K after riding with me