The SMD Traveler is intended to be used with a CCF pad stuffed in the back panel. I'm assuming the volume & compression ratio numbers above were determined/calculated without the pad. How much would the addition of a pad sway these numbers? If the pad were a standard 3/4 length Z-Lite (folded to 11"x20"x3"), it would suck up 660 cubic inches, putting the Travelers volume at 3505/2790/1850 (total/main/compressed), resulting in a compression ratio of 33.7%.
I suppose this line of thought can be applied to any of these packs as many intend for a pad to be used inside as support in some manner, but with the Travelers pad-dependent design, these extra numbers seem particularly relevant. Personally, if I end up with a Traveler (on my short list), I would rather not use a CCF pad, so I'm watching closely how well it fares in these tests.