Ed,
In theory, everything you said above is true to my knowledge. I think, however, the problem with start retards lies in the way it does the retard, which is electronically. I don't know how much voltage is required of the system for the retard to work flawlessly everytime but I have a hunch that at some point in the crancking process there is a draw down in the voltage that causes the retard to drop out and back in. That's just my own theory. I've never put a meter on it to try to find the problem. In my own experience, I have tried two different model MSD retards and either broke a flexplate or starter with both of them on more than one occasion. I took the retard out and haven't broken anything in over 2 years.
You are much more qualified to speak of the hows and whys than I am but I have never had good luck with them. It's kinda like I can't tell you how to do an appendectomy but I know that when the appendix comes out there is no more pain. I took the start retard out and now I have no more pain of broken parts.
I don't run a crank trigger although I am putting one in before next season.
One other thing...if spinning the motor over before turning on the ignition totally negates the start retard function, why isn't there a caution in the instruction to this effect? I've never seen any mention of this.
George