This is the biggest problem. What I read said you need to prime within 72 hours. Obviously all E9's and most everything else will need more than 72 hours of body work before it's ready to prime. Of course any other process that cleans to bare metal will also lead to rust, but at least it doesn't actively contribute.
Myself and a number of other people that I consider qualified agree that the 'heat warps panels' thing is a myth. Creating millions of tiny craters in one side of the panel causes the warpage. More aggressive media does not create more heat, but it does create more warpage. In the dustless process, the water does some of the removal work, and the media moves at a much slower speed in a smaller quantity, so you get less warpage.