As you can see, the xp calculation was 375 for everything. 375 just isn't that much, so what can we do to make up for that? Well, for one, they don't have a four player party. That's an immediate disadvantage as far as the rules of the game are concerned, and worthy of an xp bump. They got roughed up before hand (even if they made the save vs starvation/fatigue, they still had to suffer through it/save against it) so that's worth a bit for hardship. And if you had them fighting naked with weapons not of their choice, that's it's own level of cruel cruel hardship (and completely in keeping with gladiatorial combat).

All together I would give them double normal xp (750) and then tack on another 250 or 300 as quest experience for earning their freedom. Which, in a 3.5 game gets them to level 2, in a pathfinder game...well, it gets them closer at least.