4 part Tier 10 vs 2 part Tier 10 for assassination rogue

[jlarss]

Hello, I'm playing as an assassination rogue. We just downed LK25hc so I got access to pretty much all the gear in the game and I was wondering if it is worth getting 4p T10?
I have read that 2 pieces is better if you get the BiS offpieces but I have also seen alot of high end rogues that uses 4p T10.
I currently have T10 gloves and legs at ilvl277 and Geistlord's Punishment Sack heroic, Cultist's Bloodsoaked Spaulders heroic and Ikfirus's Sack of Wonder heroic.

Would the 13% proc bonus give me a boost in dps compared to my current gear?

[Diahi]

Spreadsheet it.