Personally, I use this one for combat and RogueAssassin for Mutilate Spec. The thing is, Itemization is quite different for Assassination and Combat. Combat rogues Hit Cap and Expertise cap, and then from most important to least Haste > Spell Hit Cap > Mastery > Crit, whereas Assassination is Hit+Expertise cap and then Mastery > Spell Hit Cap > Haste > Crit. Last spreadsheet I ran in Full bis, Combat was ahead, and as mentioned on other posts the Daggers are very viable for Combat because the Damage loss from a slow weapon is compensated by the 45% Increased damage for SS and RvS, which in fact puts it .1 Speed even slower than other 1h Agi Non-Daggers, putting it at BiS Even before the first transformation pre-heroic, If I read correctly.
If you only have 1 set of gear, I would go with whichever spec your itemization leans toward, and work on building a second set. The new 5 mans helped me finish my 2nd set, as I just took interest in combat because we now have someone to apply the buff I used to provide to casters for the raid group.
Strictly speaking CC's, This one seems to have higher performance for combat where RogueAssassin has higher performance for Assassination.
Hope this helped.