It took me longer than I care to admit to figure out what was going on with all these threads, but ohhhh, I get it, there have been some topic splits! (...right?)
I'd love to see more stories like Price of Freedom. And although Greece didn't have the action movie appeal of the Coliseum, the wars between Athens and Sparta provide so much material that could be used in a storygame. The entire work force of Sparta was made up of slaves called helots, they were owned by the city itself and the system was a unique one. I've seen them compared to serfs but it wasn't quite the same.
There were times when both sides established outposts close to the other's territories to entice slaves to escape. 20,000 slaves from Athens escaped to join the Spartan forces who had set up literally in sight of the silver mines where their labor funded the Athens navy.
Slaves in the mines were treated pretty harshly, while craftsmen may have had a good life, although slaves were still slaves.
Aristotle wrote about them more than the others so he had the most damning quotes associated with him, but to our sensibilities it was a messed up system all around. They don't seem to have been regarded as people who had been enslaved, but just slaves, almost an entirely different species despite not having many racial or cultural differences that historically made of easy to "other" people, in the American South for instance.
Any realistic storygame set in Greece or Rome however might have trouble getting around some of their other practices which were a lot worse to modern views than slavery.