While not confirmed yet, as per http://make.wordpress.org/core/features-as-plugins/ the Front End editing feature may debut as a core feature in WP 4.0.
I’ve tried the current versions of Fastline Page Builder (lite) and WP front end editor and seen that there’s conflict between the plugins: it seems like page builder is saving posts on a parallel DB table instead of the standard ones.
Whitch are your plans to integrate with WP Front End editing feature? Do you have an alpha testing version to share?