While this is a cool gimmick, and I'm no Rachel player so this probably doesn't mean much coming from me, but I feel like her regular oki is already so strong that she doesn't need to use something like this.
Barrier Blocking and aerial DPs (like from Ragna or Makoto or even Mu in Extend) would expose it hard and turn the offensive momentum of the match around. And since this requires throwing the 5B meaty, you can't really bait against those options, where as I've been baited pretty damn hard with her normal oki set-ups.
I'm just saying, gimmicks are never a bad thing to have, they're amazing to throw out every once in a while. I just don't know if Rachel can afford to lose a chance to work her really good oki game.