I love what you've done, but I would concur with Beefstew that sometimes Harry talking to himself is just Harry talking to himself.  As he and Uriel agreed in GS, the shadow's whisper was effective because it fit into a pattern of behavior: Harry blaming himself, railing against his own limitations until some idea comes to him.

I personally want to know whether every wizard out there has their own version of id-Harry in their mind or whether it's just that Harry is nuts.

I've always considered Harry a bit of an obsesive-compulsive.  IMO, to the extent that Elaine has more talent, Harry has: 1) more raw muscle; and, is incredibly more focused on improving, considering his life experiences to date.

Harry is going to grow into a more impressive wizard, over time, for that reason.  The best engineers and mathematicians I know took home books on non-linear math and read them for *fun*.  Harry is into this stuff.  Elaine I think has issues and while I see her as talented, she seems more likely to plateau.

On the other hand, she might be so thoroughly traumatized by her experience at the hands of Justin and so driven to make certain she is never a victim again that she adheres to a fanatic regimen of study and self-improvement.  A bit like the medical student whose close friend died of cancer who studies fanatically to enter into med school and/or to work as a research scientist.  Highly motivated.