I am switching to Grapefruit-Seed-Extract with P&B shakes now, too. I think it might even be better, becuase it´s liquid and so can work with the shake better (going in every corner of the gut).
It´s probably fine to take instead of Caprylic Acid. I think CA is more powerful, but it seems like the Candida gets used to a antifungal medic., so here my advice: use gse in the shake and when it´s done, get caproil (liquid caprylic acid) for your shake.