Yeah, I suppose if you were unsure about doing Hermione or Ron justice that would be a good reason not to feature them hugely. I hope you're not offended by what I said - I love your stuff! - I think I've probably just not written enough to see how difficult it can be to stay as true to canon as possible.
..and I'll probably turn into a hippocrate and hardly feature them in what I write from now because it's too difficult lol. *headdesk*