I actually walked into a cheap Hong Kong tailor with this exact photo and had the tailor make me the DB waistcoat that the guy is wearing in this photo (it's from a Phineas Cole lookbook, which was mentioned earlier). Wasn't ready to spend lots of $$ getting it done by a real tailor, but thought it would be worth just trying out. It turned out exactly as mediocre as I thought it would, but I still wear it every once in a while to switch things up. Anyway, the reason I bring this up is that, if I were to do it again, I would get a single breasted horseshoe/U shape wasitcoat. I think black tie looks better when there is slightly more shirt front showing, and my double breasted waistcoat covers more shirt than I would like. Just my two cents.