"I've heard that soda blasting can stretch and warp the metal."
Where did you read that (about a non-industrial-grade soda blaster)?
Nonetheless, for a variety of reasons, I got rid of my two soda blasters (sold them quickly on Craig's List).
In my large blast cabinet, the media is plastic-bead and alumina. I only blast relatively small items that have been cleaned of all paint, oils, and loose rust.
Luckily, I found an industrial blaster for the sheet metal (and frame) my last two trucks. They changed their media and technique/power to blast everything at an incredibly reasonable cost. Since they were used to using epoxy primer, they also "washed" and primed all pieces.
Another possible "industrial" blaster is a grave stone seller engraver.
Good luck choosing media for home open-blasting (or, in finding a consensus here, or on the Internet). The possibilities are similar to choosing a particular religion, or not.
