I have a strong concern about bloat in the dark melee set. I dunno if bloat is the right word for it, but we're already factoring in so much crank damage with how dark melee's T8 is part of its base rotation in most builds.
Amping Dark Consumption to a nuke-level attack means that, in a theoretical situation, someone would ideally pop Soul Drain, get upwards of 40-50% bonus damage, and immediately rip out with an Extreme nuke and annihilate an entire group.
On top of this, let's take a theoretical build, a Dark Melee/Shield build, where we also have Against All Odds to the mix, adding another big chunk of damage bonus. It might just be too much giving to Dark Melee. Let it have some AOE difficulty, but keep that sweet Shadow Maul cone boost.