@Cryect:
I am not checking the code, but it seems like you know what you're talking about. I am just gonna trust you on this.
Actually, this is quite a big flaw in RAWR math - not taking combo point wastes into account is significant!
I do understand, that ArPen's efficiency is greatly influenced by all the other stats. But for example, I've got nearly the same stats as boevis, look at this:
I checked every raid buff/debuff except Draenei Hit and Trauma.
I am in cat gear and talent build on the armory. Perhaps you could load my char into your RAWR and test it yourself. I'm even a bit scared, that I'm doing something terribly wrong, but I just can't find it...