As I understand it, Insanity isn't actually balanced with the game's challenge model in mind - it simply cranks all the numbers way, way up in order to cater to the masochists, regardless of whether doing so breaks anything.The short, clipped responce RPG netters don't want to hear (so I'm posting it here)? If someone can finish the game, it's not broken. It's just that your not good enough to do it.
Caveat: If you have to load and save every five seconds, that makes it sucky gameplay IMO. But it's not broken.