It could be that your reward comes at the end of the game when you have defeated the mind flayer tadpole in your head.
I think not being destroid by the ceremorphosis process is kind of a reward xD (There will probably a sweet spot where you can get stronger via tadpole but not get turned,what I wonder is if you're going to end the game with the tadpole inside you or you'll removet it at some point,and if you do,why do you retain the tadpole powers?)
And yeah usually on bad playthroughs you get more money and stuff,that's the way it goes. And then you have some exclusive harder quests for the good ones with strong gear or something so you get good things no matter your alignment.
