Steve...'scuze my ignorance of the tech aspects of the Big E, but are those scribed lines supposed to be part of the deflector shields grid (I've always thought so), or weld lines for the skin panels? If the former, I can see them as concave, but if the latter, I can see them as being convex.
I'm familiar with the 'debate' of having the lines, but I'm of the school that they should be shown in a diminished state, or 'lightly scribed', i.e., penciled ('studio lighting washout effect' aside).
I personally see them as canon, although not as noticeable as they have been shown on the refurbished original 11-footer at the Smith. I seem to recall my old AMT Enterprise model kit as having them on the top and bottom of the saucer...I don't know if that's considered 'accurate' today, but I thought they looked cool! :cool
Rob