Apples, This is a little bit apples and oranges
First Galil use AMC drives, but it can be anybody's, which as you say are ±10vdc analogue drives, these are relatively non-intelligent drives as they rely on the servo loop being closed back to the controller, which would be the Galil card or whoever's.
Due to the fact that through-the-parallel port servo systems do not close the loop back to the PC, they rely on semi-inteligent drives to close the loop, so the encoder has to return to the drive, rather than the controller.
Supposedly, if it gets off the ground, the Brain that is being touted as a closed loop control, there a quite a few benefits from true closed loop, electronic gearing being one, If they get the ±10vdc analogue drive feature working it will allow a larger selection of drives, for e.g.
Systems such as Mach, give up a few possible features for the sake of economy.
Al.