Grognardia points out a Fighting Fantasist post on all-d6 weapon damage. It’s actually more of a description of hit points, using the “measure the life expectancy of the characters under fire” description to justify all weapons doing the same damage.
To be honest, there are a number of things I was looking forward to in my since-abandoned Swords & Wizardry White Box game, and all d6 weapon damage was one of them. Another, which Fighting Fantasist also went with, was the removal of class weapon restrictions. I did the same thing. Since all weapons do the same damage, why tell the magic-user’s player that his character cannot use swords?
It also would have gone quite well with my Clerics as Mystic Warriors plan, though this isn’t necessarily dependent upon all-d6 damage. I’m going to use the mystic warrior concept in my Labyrinth Lord game instead of the more overt religious cleric design.
Something that I think is important to keep in mind when considering all-d6 damage is the hit dice power curve. All-d6 fits right in with d6 monster hit dice and the original character class hit dice (all d6). It is probably a little under-powered when monsters have d8 and fighters have d8 or d10 as in later versions of the game.
Though I will be using the BX-derived variable weapons damage in my Labyrinth Lord game, I do think that the all-d6 scheme has a lot of merit.