I'm running a 4-rogue party too, currently on dungeon level 8 - and it's the easiest team I had so far.
Front left: dagger rogue, skills in dagger and dodge.
Front right: unarmed rogue, skills in unarmed and dodge. He also carries the torch.
Back left: Archer. Skills in missiles, nothing else. He also mixes the potions.
Back right: Shurikens! Skills in thrown weapons, nothing else. And she carries the food supply for the party.
Back right is my favourite, okay, she's a female, thus that explains a lot.
