I've pushed some new changes into develop today, so beta testing is welcome. A better auto-tune, (still WIP), set slave mode by G-code (M608) and ability to save the bed compensation matrix, apparently that was brokeh.
Note that this new push changes a few things in the config. pid_e_Kp instead of pid_e_P etc., sensor_e instead of temp_chart_e, and the bed matrix has a new format. Check the default.cfg after installing. Would be great to run the config checker during start-up and get warnings on deprecated variable names etc.