Accuracy of Step/Dir Driven Brushless Servos

I really need some input. Does anyone have any experience with
driving brushless servo motors with Step/Dir signals? My plan is to
use the Rutex 997 board that inputs step/dir signals from the
parallel port and outputs the 0-10v signal to my Aerotech drives.
The Rutex board also receives encoder feedback. My question is: Am I
sacrificing accuracy with this approach? (or anything else?) Also,
will my encoder feedback go to both the Rutex board as well as the
drive/amp because the amp has encoder input too. Any feedback
greatly appreciated!

Mark