As it turns out, both the mirror and the mannequin were lying.

Once pinned and slipped on, it was in fact a bit too low-cut. Honestly, not by enough to matter, given that I’m going to be wearing a camisole underneath, but that wound up being moot. Because, as it turns out, the slope of the neckline and where the slope of that neckline falls really, really matters. And the neckline I had fudged was just too steep, without enough boobage holding it in place, and it gaped like all get-out. Really, it looked awful.
So! Third time’s the charm.

On the bright side, I really do think it’s going to work this time. The (tentatively) right solution wound up being the one I discarded at first for being “too simple to work right”: knit the neckline as specified in the pattern, fiddling only with what row of the sweater I started it on. On the other bright side, I can say with confidence that this yarn rips and re-knits like a dream! On the third bright side, I’m almost done re-knitting. I think I’ll have the front pieces out to re-block tonight (have already blocked the back and sleeves), and tomorrow I can start on the collar trim and the tie.
I’m thinking that I’ll need to insert some kind of fastener on the inside of the sweater to hold one, and possibly both fronts, in place. The yarn is really slick, and I don’t see the tie being as foolproof as I’d like when my tummy is involved. 🙂 What do you folks recommend for that? Snaps? Velcro?