Thus, IMHO, if one were addressing a stranger, the use of "braces" would be (marginally) preferable, as somewhat less likely to lead to confusion.
Except that to a stranger in America, "braces" mean things that hook to your teeth and straighten them, or a part of a building, or something that holds parts of your body straight for medical purposes, and the use of a British term to describe something we have a word for would seem affected. Just like you wouldn't refer to the new "jumper" you bought, just so you could explain what it meant, only to be asked why you didn't just say "sweater". And to the original poster, to avoid confusion, what you are calling "single chest" is usually referred to as "single breasted". Just so you know; no offense meant. That was a cranky-sounding post, so, sorry, but I'm not going back and editing it for niceness.