I think one of the problem's with the voice is that it sounds forced, not practiced. One of the reasons why I think Kevin Conroy works so beautifully is because you believe that Bruce actually has spent years training his voice to change on cue. I didn't buy that from Bale's voice. Even Micheal Keaton's Batman voice wasn't as guttural and rough as Bale's is. That being said it's not that bad.
I like to look at both Nolan films like this: "Batman:Begins" is a Bruce Wayne film. Bruce is the center focus of the film, it depicts his journey into becoming Batman. While "The Dark Knight" focuses on Batman and the consequences of his war on crime has had on Bruce Wayne and those close to him. I believe that "The Dark Knight Rises" will conclude with a sort of balance happening not only between Bruce and his other self (i.e. he will finally accept being Batman along with all the responsibility and repercussions in doing so) while Gotham City will finally accept Batman as their protector and guardian. Their Dark Knight. This is why I think "The Dark Knight Rises" works well as a title.