yo, I'm sure others will give their experiences on these products as well as Rust Bullet, POR, etc.
Problem is that although when one removes surface rust, there is most likely rust on other side of a panel or area that is inaccessible with out cutting out portions, such as rockers at B Pillar.
Now, for surface & under panel Rust I use RustOleum Professional Rusty Metal Enamel Primer 7769402 then applicable top coat and clear coat.
I saved $ by not using Rust Bullet or POR..and have same results as shown on my steel lawn bldg. roof as well as the Bronco's tailgate and lower 1/4s