Have ordered the Night Breaker + in December 2010. The search for the durability of the "new" had unfortunately made for me a satisfactory result, so I had to just test yourself. During a first test in the dark I had to look very closely to see an improvement in the illumination as compared to the previously installed Bosch + 60%. This is really only marginal. You have to understand that at a Approved H4 bulb of maximum luminous flux by law to 1000lm (I believe +/- 15%) is determined. That framework therefore no legal-to-use lamps fall out. The only difference to a "high-performance lamps" brings is more even illumination. This is possible because the filaments have smaller dimensions and the light source is characterized Point type. Unfortunately, the smaller dimensions of life are not very conducive. In effect, the lamps have kept with me about 10 months (December to September). In summer, however, I am not driven a lot with light.
A distinct difference, however you could see right when you first turn compared to my old lamps. The light color is really noticeable white (but still bright yellow) and when using the high beams really almost white without yellow tinge. This looks naturally pretty chick from;)
I have now ordered my next once the Philips NightGuide and will report how these be translated in comparison.
PS .: In the rain I found the brighter light rather slightly worse than the "normal" yellow. Considering the example compared to the Philips X-treme lamps quite low price, the NB + I get, despite the rather low life and the imperfect performance in rain 4 stars.