What kind of oil are you running in your truck now? As for Hot Shot Secret, yeah, it's suppose to help eliminate a stiction problem that is more common with the 6.0's. I wouldn't run it in a 7.3. The best thing for the 7.3 is run a high quality oil and keep it changed regularly.
I doubt that you will see much difference switching. Amsoil makes specific oil for specific applications. What they recommend for newer trucks may not be the best to run in our older trucks. They have a good staff on hand, and it might be a good idea to ask them which they would recommend for...