Interesting to see how the different lighting schemes work out. The back lit look is definitely functional, but not very atheistically pleasing. I'd like to see it with the modifications you mention (tighter falloff, a visible light source), but I suspect it still won't look right. Part of the problem too is that we're all used to the illumination scheme from TMP, so anything diverging from that is going to look wrong.
I also want to say how much I like you take on the ship too, it's very very nicely done. Your TOS Ent, together with Deg's and Cary's have been a real inspiration for me. I'm trying to do my own 'update' of her, and it's great to see how you've tackled the same problems we've all run into; the downside is that I like some of your solutions so much that I have to be careful not to simply copy what you've done.
I'd love to see what you're thinking in terms of the connections between the dorsal and the primary and engineering hulls. The lack of any detail or even a blend is something of an iconic design feature in itself, so updating that look is going to be challenging.