Can I allow users to access the Dashboard or edit Posts/Pages?
The short answer is no. s2Member's design is focused on "members" of the site; i.e., people who access the front-end of the site. We do not offer support for backend administrative access in s2Member.
The longer answer is yes. By default, s2Member does not support allowing other users to access administrative areas of the Dashboard. However, many site owners have used s2Member as a framework upon which to build such an integration. The article here regarding s2Member Roles/Capabilities explains how it integrates with WordPress, and it should be very helpful for developers who are trying to determine a list of next actions needed to complete an integration of s2Member where the business model they are working with will allow some users to access the Dashboard too.