IMO- You need a healer to hit your top end damage. With cloak of Anni, cloak of carnage, defense forums, and other talents that benefit from being attacked. (Cloak of pain is up almost 100% of the time). At least as Anni that's how I come close to 600k in a Huttball.
As far as your rage to anni to carnage I get about the same difference in damage for each spec. I find rage to be about 10% more damage over Anni and Anni 10-15% over carnage. Though I tend to survive better as Anni and I like to sit on healers.
I agree we take a bit to ramp up but our top end seems more then competitive with the top end of other classes.