I do agree with you that it's a good indicator but it's also a known weak link. All of the current for the car goes through the amp gauge and this would not normally have been an issue back in 1969 but the wiring and bulkhead connections have aged. Couple that with the fact that newer accessories (ignition, higher performance lighting and audio systems) draw a lot more current through these wires and connections and you have a recipe for disaster. I have seen these gauges melt in the dash.. My modifications only effect the voltage going to the regulator. If it's not a steady voltage then charging is going to be erratic and therefore the lights are going to flicker. The MAD alternator gauge bypass is what eliminates the alternator gauge. I have done all of that as well and believe me I like an amp gauge much better but for the above reasons I modified the system.