Can I run s2Member + BuddyPress + bbPress?
Yes, s2Member comes pre-integrated with both BuddyPress and bbPress.
Forum Software w/ a Twist; from the Creators of WordPress
The bbPress™ plugin (forums/topics/replies) integrates seamlessly with WordPress and s2Member. If bbPress was already installed when you activated s2Member, your s2Member Roles/Capabilities are already configured to work in harmony with bbPress. If you didn't, you can simply click the "Update Roles/Capabilities" button; see: WordPress Dashboard → s2Member → Other Integrations → bbPress. That's all it takes. Once your Roles/Capabilities are updated, s2Member and bbPress are fully integrated with each other.
Social Networking Software; from the Creators of WordPress
The BuddyPress™ plugin (for social networking functionality) integrates seamlessly with WordPress and s2Member. BuddyPress is a powerful plugin that takes your WordPress-powered site beyond the blog with social-network features like user profiles, activity streams, user groups, and more. BuddyPress comes with several components that integrate directly with your site, with each other, and even with other plugins (like s2Member).
s2Member comes pre-integrated with BuddyPress registration forms, with BuddyPress profiles, profile fields, and it's also possible to integrate s2Member Custom Registration/Profile Fields into BuddyPress—instead of using BuddyPress-generated profile fields. The choice is yours. See: WordPress Dashboard → s2Member → General Options → Registration/Profile Fields to learn more.