Do think the death of Heath Ledger has.........

actually, with The Shining made before Batman one would think that the audience would buy into Nicholson fitting the Joker's persona even more. it's all relative, but i think Heath's death make you feel the character is darker and he did have Jack's performance as inspiration while filming so he could see how to personally make the character darker. to say his emotions and personal life "spilled over" in his work is uniform with any good actor, they convey their life experience through the character and the whole of their emotions... you can't act without identifying and referencing emotions and feelings