Well, a few things.
I do know a few good combat rogues that are pulling the +2k DPS over you that you're referring to, and they all gem straight AP, and also have around 100 more hit than you. Most combat rogues I see have in the range of 450-500 hit. I can do about the DPS you're talking about as combat in mostly 245 gear. You also didn't mention what rotation you're using.
The only glaring thing to me would be to get your hit up to at least 400 if possible. With the trinkets you have, you're on the borderline of whether AP gemming or arpen gemming will be better. I have a feeling you'd see more DPS from AP gemming, but that's a big investment just to see.
"Sometimes attaining the deepest familiarity with a question is our best substitute for actually having the answer." -- Brian Greene.