As someone who is currently able to play at moderately high rating as Assassination I keep worrying and actually finding it surprising that this hasn't been nerfed yet, but I don't think it's going to happen because of what that would do to Rogues in raids. I'm also not sure it would necessarily qualify as that OP as it's still largely underrepresented for the most part. It feels like being an Unholy Death Knight with only one trinket instead of two, and not near as potent burst. It also is not effective against teams who know how to remove poisons, pop AMS, cloak etc. to avoid the damage altogether.