First question I would ask, is if you need to remove the paint? The original primer can make a good substrate. It really depends on the current state of the project and the amount of rust.
On my project, I blasted the paint off the bottom, boot and engine bay. But the exterior paint wasn't in too bad shape. So the paint guy sanded it down good, fixed problem spots and we went from there.
Most gus I know sand blast their cars. The down side to blasting is it leaves grit everywhere. I don't know anyone who chemically dipped thier car. From what I understand, the down side is that if you don't get all the dip out, it can creap out later and ruin your paint job.