I have to share registrations and memberships across two sites. I have 2 websites, both with only pages, no blog or anything - just the main one with some pages that all visitors can access, and some that only Members can access on 5 different tiers, 2 free, three subscription - and the subdomain that has Marketpress with a retail store area accessible by all visitors, and a special store just for the 4th & 5th tier Members. Most importantly, this Membership tier system doesn't allow the prospective Member to choose a Membership level -there are triggers that move them from one level to the next - Tier 1 they have to register to access the Membership application, 2 is the application process, 3 they pay their first monthly dues, then 4 they purchase a start-up package, and 5 is an Active Member. There are a number of forms that come into play during this tiering process. We use Gravity Forms for that.
So, with all that background, my question is, can Membership be set up to accomplish these things? To integrate with Gravity Forms, and Stripe, and carry the login and Membership tier data/permissions across the two sites with Multisite?