I have this unit on my l18 powered 510 and love it.
My dad was always changing the points on his 510's and got the accel optical setup later on, but as others have said, its not as reliable when dirty or in really dense fog for that matter.
If you use the ballast, it seems the spark is way too weak and won't run at idle.
I am using a 3 ohm 40,000v accel coil.
I don't think not using the ballast is fine, as the current doesn't go through the pertronix unit, but os more of triggering switch telling the coil when to fire.
I may be wrong, but I have had the ballast bypassed for years with no problems. I even gap the plugs to .040"