I have been using S2Member for about two years now and S2Member Pro for about a year. They are the core of my business. I create online psychotherapy conferences for psychologists and others in the helping professions. These conferences are a way for them to stay up to date on therapy techniques and strategies. My largest conference to date is the Milton Erickson conference which has over 40 presenters.
I used to consult on SEO and landing page optimization projects, but thanks to S2Member, I know spend all of my time working on my own projects.