I dunno, the Vince dress seems pretty straightforward TTS to me. I tried on a 6 (only size available) and it fit me in the shoulders and bust pretty well, but was slightly too small in the hips, so a size up in an 8 would probably have worked, and that's pretty typical sizing for me.
However, I can't help but feel like a big loser that a dress that works so well for so many of you is decidedly non-fab on me. Bah.