Member Based Multisite Installation - Order of Operations

I am creating a member based multisite installation and want to make sure I am setting everything up in the most efficient order. Visitors can freely view the primary site, but cannot view the sub-sites (content) unless they become a member and create their own site.

1. Multisite installation (complete)
2. All primary pages are published and in place. (complete)
3. Using New Blogs Template to generate new site (complete)
4. Using Gravity Forms/User Registration for Further Customization
5. Membership Plugin OR Pro-Sites? The membership levels will be based primarily on the number of posts published monthly. The majority of the upsell options available in the Pro-sites plugin do not apply at this point.
6. Custom Post Types plugin will be used
7. Marketpress - (Hiring WPMU developer for this custom piece.)

I'm kind of at a crossroads as to the next step. Thank you in advance for all of your advice.