Twelve-Sided Surprise

I am thinking about replacing the d6 skill rolls in Dungeons & Dragons, Labyrinth Lord, and especially Lamentations of the Flame Princess with the d12. As a referee, I need more wiggle room to apply the occasional bonus or penalty to a roll, and with LotFP in particular I'd like to make the rate of skill improvement slightly more gradual, but not as sluggish as the old d100 progression in D&D. In order to preserve the sense of consistency, I might switch initiative and surprise rolls to the d12 as well. Too radical?