Horay! Thanks very much for being the one to do this well
Just a few points... mostly because they disagree with stuff that i've found in other places, but more than likely, i'm incorrect, but would like to see what everybody else thinks.
Firstly, these two tie together, but I personally go for Felhunter as pet. Theres a
big emphasis on CC, and being able to interrupt and silence (albeit for 3 seconds) mobs is really handy. Indirectly it can be used for CC, since I've been using it to silence casters that need to be pulled into traps. Very situational, I'm aware. But my second point helps too. (see below)
I use Glyph of UA instead of Lash of Pain, since I was using the felhunter, I took this glyph instead, and then the DPS added by succubus is at least evened out a little bit by this. I've also read somewhere here, but cannot remember which thread about the DPS difference between the succubus and felhunter being minimal, granted simulationCraft is a bit strange the way it calculates some of the damage of pets, but I wouldn't say all out that the succubus wins hands down.
Last point is Affdrain and haste VS mastery. There is proof that yes, when you're using BiS, mastery will increase DPS over haste. My argument being, is that mastery doesn't affect
all spells/talents the same that haste does.
My point being is: If you can perfectly time all spells, priorities and rotations, then yes, stack mastery. For the rest of us mortals (read panicked hotkey mashers), would it not be better to push for that 2nd extra tick with haste (2.6k+) instead of stacking mastery? I'm just looking for some discussion on this, because I've not really seen it checked out in detail.