[Wotlk] Dagger rogue pve, Assassination vs Subtlety rogue in PvE?

From what i've read both of them are sub-optimal PvE specs, but if one were to go dagger rogue and not combat, which would be the better performer overall in PvE? I like playing classes/specs that not many others play (Throughout TBC i'm maining spriest and doing it quite well, and spriest is not rare, but havent been in a raid with more than 2 yet). I would stay with shadow for WotlK too, but honestly it is getting tiring a bit in TBC and i am looking for something new in WotlK.