Okay, well there's some big decisions to make here--there's the possibility of a change in direction for how to handle the back primary hull/impulse engine assembly.
It was brought to my attention yesterday that there was another way to interpret the transition form saucer to impulse housing, which seems to have some advantages. So I've mocked up a basic shape for it to see how it stacks up against the prior version. There's a few problems that would need addressing, such as finding a satisfactory way to thin the impulse engine down to its former thickness while keeping the lines looking nice. I'm torn. I like both of them, but for different reasons.
Orthographic views of the new approach:

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Comparison between old and new:

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So. Pros: Sleeker lines, a nice tapered shape on the top of the saucer in back and a naturally-occurring slant where the pylon meets the hull, in the manner of the
Reliant.
Cons: Aforementioned slant slopes the opposite direction from how it is in the painting; if the lines are kept straight, the impulse engine is much thicker than in the painting, and the secondary hull has to be moved down. An upward curve on the bottom of the rear saucer starting at the back of the pylons would fix that, though. And of course, I would have to rework most of the detailing I've already done in that area.
I may also be able to adjust the shape of the saucer I have now and join it into the impulse engine on top, to get that nice taper shape without having to remodel the whole thing.
As it stands, I like the current version as it channels a sort of "ILM" vibe, due to the use of separate shapes all kind of intersecting each other. But the newer way has a nice, TNG-era, Andrew Probert-y kind of blended elegance that works well, too.
Thoughts?
EDIT: Here's a sort of "compromise" version, created because it looks like getting the right amount of detail into the saucer mesh as-is just won't work. It's not quite as graceful as having it all be one piece, but....

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