Retrofitting question

I have a Clausing Kondia FV-1 that I got for a really good price.  It was fully functional, the guy ran a program on it for me to demonstrate everything was working.  It has a Dynapath Delta 20 controller on it, which I understand was a decent controller for its time.  I can either learn to use it in conversational mode, or drip feed it g-code from a laptop. 

It would be really nice to have a more modern interface to it, so I started out with a plan to use a Mesa 7I77/7I92M combo to drive the existing amplifiers.  The existing amps are fed signals from 1000 ppr encoders, and a tachometer. Now that I'm actually digging into what is required I am wondering whether this is the best course of action.  It's just a matter of time until one of the driver boards or something goes south and I will have fewer options than if I choose a different path. The wiring is also pretty complicated.

I am thinking that switching to a 7I76 card, I could then use more modern step/dir drivers like the DG4S-16035 servo drives, simplifying the wiring immensely, and tuning from what I understand.  The old Servo Dynamics cards go for more than this on Ebay so it would likely pay for itself to switch.

Would the DG4S drives perform the same as the old SD amplifiers?  I know I may have to upgrade the encoders to get the best performance from them. Are there any pros versus cons to be aware of?

Thanks in advance for any feedback you can provide.

Jeff