Here is the response I received from the Pro Series e-signature desk

This is a common question and the short answer is that the ERO requirement is automatically fulfilled when you use our e-signature to send and receive 8879’s. Since you are sending the request directly from your software which has your EFIN attached to it, our system assumes you are signing the ERO and prepares it as such. We took every step to make sure we’re IRS compliant while making it as convenient as possible to you and your client. The IRS does a much better (although wordier) job of explaining it than I can. Feel free to reference this article for further clarification.

https://www.irs.gov/irb/2007-42_IRB#NOT-2007-79

We are going to use the Pro Series e-signature add on this year so we appear to be in compliant.