[mactec54]

There are features that you get with combined controller closed loop that don't come with independent closure.
Electronic Gearing, electronic cam, constant surface feed etc.
Al.

Electronic Gearing is part of all quality intelligent Servo Drives, and has been for at least 25 years, constant surface Feed used for lathe's mostly, is a G-code function, which is part of any good control software, or can be stand alone with a constant or adjustable pulse train from a control to a Servo Drive

The servo drives davemorl is using have electronic gearing