As an extreme test I had a small section of a panel garnet blasted blasted and another soda blasted and left them outside. The garnet blasted panel was coated by a black etch primer and the soda blasted panel by a protective clear that does not impede welding or automotive primer adhesion.
The garnet blasted panel started to show signs of etch primer deterioration on the edges first then slowly worked its way towards the centre of the panel. This was really a test of how long the etch primer would stand up to the elements. But it did not break down on the whole surface at the same time. It was months going on years before the whole panel was completety rusted.
The soda blasted panel lasted less time but started at the edges and in varied spots all over the panel indicating that soda did not remove the initial rust on the panel. The panel was fully rusted in about 4 months.
The information is supplied to make your own conclusions and I admit the test was extreme but the panels where placed side by side in a non shaded spot exposed to the outside elements and looked at monthly.