Barry, I really appreciate your passion for what you are doing. Let me as you a few more questions to fully understand what you have found.
How about any flash rust that is bound to exist on bare metal? If you have a little flash rust the acid in the etch is going to "convert" it. How did the epoxy hold up when a little rust is present?
For that matter, was the condition of the metal always the same (I sure assume that is a stupid question being THAT would be the most important thing when doing a comparison test).
I am fascinated on your findings. I know you don't want to toss around brand names and for that matter, it shouldn't make that big of a difference anyway as long as they are like technologies they should be "pretty close". But was that etch of S-W's that worked the best (as I remember you said that) the Vinyl wash? It has PVC in it which makes sense that it would be a special product.
Listen, I have no allegiance to S-W, I hardly did when I was an employee. The truth is the truth. I have a lot of respect for them as an employer. They treated me very well as they do all thier employees. I can't say enough good things about them in that respect. As a product, I know the weak points as well as the strong. Facts are what I am concerned with, not emotion.