I voted for the FAA standard - FWIW I think it's much better to integrate with an existing standard used around the world than create a new one that causes confusion for all other pilots within the NAS...
DJI A2 flight controller, barely flown (installed, bench tested, then flown for <30 minutes before mothballing S900). Boxed, in excellent condition, with Compass Pro Plus module and DJI CAN-hub.
$550, offers considered