Hey Matthew,
Great post...given the choice, I would pick EO . Fragrance oils (FO) fall into the FDA's juristication and their "trade secret" law. So, this means is that the manufacturer of the FO does not have to disclose the ingredients used in making their fragrances. basically, you may never know what in the world is in an FO, but guidelines (whatever that means) are in place to ensure general safety of the FO.