Travis "NotFastEnuf", the maker of the BOSS frames and contributor to Project Mockingbird, brings us another exciting piece of flight experience: race mode!
Its a hybrid mode between angle and rate. As opposed to horizon mode, where you get angle when upright and rate when upside down, race mode gives you angle mode on the roll and rate mode on the pitch axis.
That means you get a lot of the smooth, speed and flip of rate mode, while retaining the fast, predictable and precise roll movement of angle mode, including the self-righting capabilities if you clip an obstacle.
If you are looking for a compatible FC, look at the BetaFPV F3!