I made the change in ignition components to allow my FITECH to control timing. It has done as the others have stated in allowing so much more control of the tune. How smoothly my car drives now is night and day difference. It has really taken the edge off the 041 cam in my Pontiac 455. Off idle response is much better, clutch engagement is smoother, engine load at cruise is lower according to the MAP readings. No downside that I have found yet.
What distributor did you use for the Pontiac V8? I've heard the 301 turbo distys can be made to work.