I would like to see this feature as well. It mainly matters in a scenario like this...
We have a free membership which used to help indoctrinate leads and get them in the site so if they upgrade it's easier on the checkout form.
But we also have a sales letter that lets non-free members sign up for a product using Facebook or Google account. Because we can only create one free confirmation page, the sales letter non-members would immediately go to a confirmation page that made zero sense to them... when they should go to the checkout form to finish creating their account.
I hope that make sense.
Thank you for this suggestion! This feature request or some aspect of the functionality suggested is currently being reviewed for possible inclusion in a future update. If there is additional information, this post will be updated to reflect it.