I was a service tech for a prototrak reseller in australia. We could never figure out the servo interface on any of the prototrak contollers. Southwest wouldn't give any info either. The only tuning options on their drives is a couple of different jumper pins that set max current. If you're changing controller, you're gonna be changing drives and motors to. If you go with the centroid dc all in one thing, you might be able to keep your motors.
I'm using Adtech and tomatech chinese controllers on my machines. I can recommend the tomatech. Adtech... Not so much, but it does work.