BuddyPress.org

Our plugin (free) Vibebp allows you to
a. Assign a default member type on buddypress registration.
b. Generate multiple registration forms and each form can have its own , member type, activation email.

Let us know if you are interested, it is built over buddypress. We are still preparing it publish it on wp.org.
Checkout this video : https://www.youtube.com/watch?v=czb0FYKcFME