This is exactly the sort of question that simulators and spreadsheets can answer for you. I know the documentation isn't perfect, but step 1 is NOT "post in the thread and hope someone else calculates the answer for me." During your day off, perhaps you'll be able to figure it out yourself.
Also, fix the character link in your profile.
I have a simple question that I tried to find the answer to within this thread and the simulation craft thread. If I have overlooked something feel free to report my post or ignore it all together. My itemization is not ideal due to my warlock being relatively fresh at 80. But what roughly is the dps increase of 4 piece bonus on a standard length fight? And would it be worth wearing 4 piece while losing: 146 Spell Power, 42 Crit Rating, and gaining 5 Haste? I understand this may be difficult to accurately give a solid number to since there are a myriad of conditions and other buffs to consider, but ballpark?