While of course in a gimped spec, SR gear, and a VW out my damage was very low, but I wasn't bothered by it because our DPS is by far our strongest aspect, I didn't mind too much. I kept him out even during P1, and thought, "I wonder if suffering works on bosses." Lo-and behold, Illidan's chance to hit was reduced by 10% for 15 seconds, I was kind of amazed by this fact, that it'd work on bosses. Given it's on a 2m cooldown, which means it can only be up 1/8th of the time, it still seems like a useful tools that Aff locks might want to consider using for tough transitions in some boss fights.
Interesting to know! Though it's hardly applicable since you should be Destro for dps anyways, and Aff only for imp/SE