I'm resurrecting this thread a) because I can and b) because I bought a d/b blazer with gold buttons, but want to swap them. I do not want a blazer. I do not like gold buttons. If you're going to tell me to keep the gold buttons, then you should look elsewhere. Here is the jacket in question, plus a close-up to get a good idea of the fabric texture.
I was originally leaning towards horn buttons, until being informed that the risk of the orphan look increases upon button swap. However, I have seen enough examples of sportcoats with horn buttons that I am unpersuaded by that argument. Nevertheless, in fairness to SF groupthink, I'm opening the discussion up to the forum population at-large. I'm debating between some manner of horn or MOP, except white MOP. That's too rakish for my work environment, and I'm already pushing it with a double-breasted sportcoat.