On my 1984 500 SEL euro-spec I went from standard 55/ 65 W to 90/ 100 W without any real improvement. The light was "whiter" alright but did not improve the visabilty. On recomendation I changed the bulbs to 55/ 65 made by Philips (I dont remember the type though) and that really made a positive difference because the light pattern was really well defined.
If You want to I can check what the philip lamps are called?
The 90/ 100 burned out faster than the 55/ 65. Probably because of the higher temp that the higher output creates or it might have been a brand issue.
Good Luck/ Mikael