There's still a gap, and I mind it.
Day 3 of dome sanding, and I'm beginning to think the problem of not having a flush fit has more to do with the top area of the inner dome, rather than the side area. Tonight I used a combination of the random orbital sander, and sanding by hand. I've sanded the heck out of the sides, to the point that any more sanding and the inner dome may start to fit too loosely. I don't want to be able to see through it. So I started sanding the top area of the inner dome, it's hard to tell if it had an effect.
With all the panels in place, I can't determine exactly what is keeping the upper areas of the pie panels from resting on the top of the inner dome, but there is still an approximate 2mm gap, and it really needs to be eliminated.
I'm considering removing the large circle of the outer dome to get a better idea of how things fit up there, but I'm not sure I won't regret that, so I'll mull it over. "Hmm..." (That's the sound I make when I'm mulling.)
The weather might get bad the next day or two, so I need to find something else to work on in the meantime; not that there's a lack of stuff that needs doing.