I haven't heard of that product, nor used it. Sounds to me like its worth a try though. I've always used a power grinder to remove all rust, and I can say that its not a fun job. The thing to remember is that rust is like cancer. If you don't get it all off the substrate, it will continue to grow under the coating.
Sorry I couldn't be of more help with your specific product question sheliap. Oh, and welcome to the forum!