BuddyPress.org

I’d just create a custom page template and create a RSS feed from a filtered, BuddyPress activity loop that only outputs blog posts.

Here’s a guide that will help you create the custom RSS page template:
http://yoast.com/custom-rss-feeds-wordpress/

Here’s the activity loop codex page:
https://codex.buddypress.org/developer-docs/custom-buddypress-loops/the-activity-stream-loop/

*Set the action to “new_blog_post”