I started off playing on torment and tried a sword / shield melee, ranger, mage and priest setup. It was abysmal and not enough damage.
Then I started a new torment game with two dual wield fighters, mage and priest and the fighters also had a single point in priest spells and though its still tough it became doable, and the fighters can usually finish off a single foe in each combat round while the mage spams daze + haste. It was made a bit easier because I knew where to quickly find bronze broadswords and iron shortswords at the start of the game, but enemy casters on torment still take loads of reloads and luck to beat, while I'm trying to finely balance strength vs endurance, and hardiness vs melee weapon skills to make sure the fighters can still hit things well and survive (having to swap stats around a lot in character editor to test, but not using any additional cheated stats).
My two casters I just leave as pure int focuses, and no priest splash on the mage as using him to heal instead of daze is just a waste of a turn. Having just 1 point in priest spells on the fighters though meant that I could use them for curing any poison, as a single priest just couldnt remove all the poisons and heal at the same time. But their heal is too weak for combat use, but good to use outside of combat to save my priests mana. Even with no investment in intelligence, they still start with 45 mana, and +5 per level, so its good to put that to use on Torment difficulty.
Its reminding me of how brutal the zeboyd RPGs were on insane difficulty (Cthulhu saves the world, Penny Arcade 3), I dont like it as much when I can just breeze through everything with no difficulty which is what happens on hard difficulty.