The DB evolved from the frock coat, which historically was more formal than the single-breasted lounge jacket that helped pushed the frock coat off the market once and for all. A DB dinner jacket is less formal than a SB model for reasons that are unclear to me, but all seem to agree on the point. Poll 1,000 people and you will find that most believe that the DB is dressier than a SB (that is, one is more "dressed-up" in a DB than a SB). That's all I said. Don't confuse "dressy" with "formal." I made no claims regarding the latter ... but in most cases, I think the DB is both. If you want "casual," leave the DB in the closet. The farmers will appreciate the gesture.