My bad about bf3, i can't remember what that kind of knockdown is.
All DD3 combos take away your health and you lose like 5% during your combo above, which I don't like.
You can do B31~ex DB1, 2 DB1, B121 BF3 for 38%. Then you can dash forward for oki. If the opponent ends up in the corner you can DD3 to start your 50/50 game and it's active entirely during next combo (if landed). Basically ex DD3 midscreen is no longer worth it, unless you want to spend all 3 bars for a big damage to kill.