I bought a set of these - and have just returned from a French holiday - and am most impressed with them.
I wired them into the side-light circuit on my 1100GS - so always on - and was amazed the amount of light they chuck out, especially at night.
I actually drove 400 miles at night, some on unlit roads, with just these lights on - a brilliant white light that illuminated the road ahead superbly, along with the edges.
Only drawback - oncoming lorries were flashing me occassionally, so need to see if I can mask some of the unwanted upward light output - shame they aren't made with a proper lens arrangement to direct the beam.
I see they also do a 27w version - can't imagine how you could get away with that amount of light output, especially at night!!
Mike