PH is right, the E6B, good as it may have been in its day, in comparison with new lamps isn't much chop, and expensive to maintain. The current standard good lamp is the Cyo. They too should be on sale as they have just been updated with daylight running lamps. I have both types, nearfield with built-in reflector and the sports type which has a supposedly further throw (I don't see it), and recommend the R type with the reflector for its better side-spill close to the rider; its reach is far more than enough for fast night work on narrow lanes and A roads.
Peter White in America has photographs of the throw of the various lamps. Pay more attention to the width of the light beam than the distance of its throw: some of those beams are too narrow to see the verge or the ditch or the pavement kerbstone when it matters.
The N72 has Ultegra-type bearings. I have both Shimano and SON hub dynamos and find differences in operation to be minimal. Unless you commute 250 miles a week, the Shimano is more than good enough; it is in any event rebuildable (at least theoretically -- for 45 Euro for a new one, I don't see anyone bothering with a rebuild).
Andre Jute