I have changed out one old style controller for the new electronic style. The electronic unit came from Sew-Classic and was quite easy to wire in.
It's not a quick change swap with those S-C sells, though it might be with other brands.
I like the way the controller works, it controls the machine's speed slowly and surely as you push down on the pedal. What I don't like is that it's made from cheap plastic and has no weight or substance to it.
Joe