Well, I just beat the game again, this time with the 3 heart challenge. It only took me 3 hours longer than my first time play. So I finnished in 41 hours with 3 hearts. The only challenge was the Arbiter Grounds boss, he killed me twice..Well, actually, those spinners on the tower killed me. In total, I died about 7 times, from Misc things.
I found it to still be a kind of pathetic challenge..