I didn't see how the surface was prepped in the comparison article, and have only actually used POR myself. But I can say with experience that POR is not a preventative at all. Billed as a conversion coating. In fact, if you simply apply to bare, unrusted steel, you can get peel and flake off. I've used POR on Jeep frames that are now 4 and 6 years old with regular off road exposure and it has held up fine. Only need 1 coat, and then top coated with rattle can black.
I'm not a chemist either, but again, with proper prep (wirebrush/removal of loose rust, metal ready application, POR, topcoat) I've had excellent results.