I'm new to this forum but I come here from time to time to read what you all have to say. I have some informitive and helpful things, I thank you! So here is my 2cents:
Sword spec overall is by far a more damaging spec than daggers. Daggers have alot of burst damage. So if your in a short fight Daggers will win in the dps race due to the sick sudden high end damage it puts out. A long fight on the other hand is a different story. Swords will or should out pace daggers by a decent margin, mostly due to the stready dps as well as the sword proc if your combat.
Ive tried most of the specs so far. The highest dps dagger output I could find is mutilate, if they arent immune to poison. Which is going to get a buff next patch.
I have a 70 Rogue, called Inkeyes on Executus. Which is my main toon. If you want to look at my spec. IF my toon has alot of resilance gear on then I was PvPing before I logged off. You should see T5 shoulders and gloves if you want to see what I'm using for PvE. I'm not the best rogue in the world but I don't do half bad either.
Hope this is of some help