I have been trying out the Control Rig and Rig Units that are in 4.21. I think that this concept will be very powerful once finished. I would like to see ways to script adding all of these nodes and hook them up with Python commands. As it stands it could be very tedious to try and replicate setups that we would have in Maya. Every time we update the rig in Maya we would need to revisit the Control Rig. I think there needs to be a way to hook up some sort of construction Python script to this.
I look forward to the future development of the Control Rig ideas.