The Cabeau Evolution S3 is the same shape, and made of the same memory foam material, as the standard Evolution. The only significant difference is the inclusion of two adjustable straps on the back that can hook into airplane seat headrests to keep the pillow (and thus, your noggin) in place as you drift off to sleep. You can even choose to position the pillow below the headrest (as pictured) to support your neck, or directly in front of it to surround your head.
The S3 is regularly priced at $40, the same as the standard Evolution, so there’s really no reason not to choose it, as far as I can see. Today’s $30 deal is also about as cheap as the old model ever gets, so I wouldn’t wait around for a better deal. Safe travels!