Gotta agree with Lord Tribble, that section of the underside looks rather off like that. I know it's kinda like that in Richter's model, but honestly speaking, he did get a number of things wrong with his model, that segmented and darkened part of the bottom of the saucer being one of them. I hate being nitpicky, especially since you're planning on taking a sabbatical from BC modding, but I really think that the original source materials should take precedence. I do realize that the movie itself doesn't have too many still shots of the big E, but there is a resource out there, and that's the starship "simulator" of the Blu-Ray's special features.
Again, I hate being nitpicky, I'm just trying to help.

She really does look great, especially that aft view.