Why would you use The Extract of Necromatic Power? I think most people are happy to agree the numbers presented on
www.shadowpriest.com are relatively accurate and they have this trinket ranked quite low compared to what you could have. Granted that
www.shadowpriest.com doesn't provide numbers that include SF, SW and other buffs the proc benefits from, have you got some numbers to support it is far better?
In addition dying curse looks to be one of the most effecient places to get hit, perhaps the most effecient... Just as a comparison, dying curse will cost you 10 PP from the next best in slot item to gain 71 hit or about 7.1 hit per loss of PP. You like the valorous shoulders in your gear setup, presumably for the hit over the best in slot item which is the Mantle of Dissemenation... just for this slot you are giving up 20PP for 41 hit which is about 2 hit per loss of PP which is a lot worse than utilising dying curse.
I can't see how that could be the best setup for that reason.