Using Pro Sites, when I try to register and start a site using the wp/bp registration system, the paypal button redirects back to the package options page. However, if I disable the wp/bp registration in Pro Sites, it works just fine.
I also noticed that the user gets a live site right away without the payment (which is fine for now as I am trying to collect pre-sign ups before a full launch) using the wp/bb registration and the option to fillout the site form is always present whether or not user selects to start a site.
Disabling the wp/bp registration, user has 48 hours to pay before site is active, but it doesn't seem to listen to the free-trial period. I was using the free trial period to collect sign ups with out immediate payment.