Pro Sites and BuddyPress registration

Prior to activating Pro Sites I had my site's registration experience laid out pretty much exactly how I wanted it -- visitors could choose whether they wanted to set up their own free blog or just be members of the community, and the sign up page was customized for this particular community. I wanted Pro Sites to be on the back end to offer those with a blog the opportunity to upgrade and get more/better plugins and themes, but I didn't want it taking over the initial registration process.

Now, when I try to register as a new user all I get is a page redirection error (The page isn't redirecting properly . . . Firefox has detected that the server is redirecting the request for this address in a way that will never complete.) as the link that should take me to the wp-signup.php page is tries to go to the Pro Sites registration page. Since I can't get there, I don't have a clue what it looks like or if it taps into the registration form that I already had in place.

Is it possible to stop Pro Sites from taking over registration and keep it in the back end to allow upgrades? If not, is there another plugin that would allow the site to function that way?