Q: Now that he sees how the story line opens up and the potential of what would basically be third person POV does Jim regret writing in the first person?
Oh, not just no, but hell no. I mean, I couldn't even imagine doing that now.
Q: What made him choose first person for Harry?
Debbie Chester, my writing teacher.
Remember that I wrote Storm Front in what was basically a bid to show myself how wrong my writing teacher was and how right I was about my work, so I resolved to do everything her way for one book, just to show how awful the results would be.
I had been struggling with third person--especially with being able to make characters who were sympathetic and emotionally viable--and Debbie suggested that I try writing something in first person viewpoint and see if it worked out any better.
It did. I had a much better instinctive grasp of first person than third person. My third person writing is STILL not up to the kind of speed I'd like it to be--but I've done a lot less of it, too, and it seems to be improving steadily, if not monumentally.
Jim