I would risk a statement that yes, they have it better. They can at least strive for a better social standing (though we know little about Rauatai and Vailian Republics social strata). Can a roparu change his caste? Sorry, chump, maybe in the next life. You must live above a great pile of bodies of less fortunate members of your caste which you didn't choose yourself! Feel free to take anything you find particularly tasty from that refuse pile, bro!
They can strive for a better social standing. But for most people in Eora (and sadly most parts of the real word), that's just an illusion. And even if they are somehow "responsible" for their social standing (not being intelligent or assertive enough, making mistakes, etc.), do they really deserve their fate?
At least, in Huana culture, people seriously believe in the responsibility to care for the wellbeing of the lower caste.
Obviously, there are very different opinions on which side is the best/worst. But that's just a sign of good storytelling.