The product page has been updated to list the volume as 10 L.
The Luminary has a very streamlined design, it reminds me of the 1950's locomotives.
It's aim, I believe, is to be the backpack equivalent of the Pop Tote, it is perfect for an hotter temperatures EDC, in town.
It holds a phone/ tablet/ fablet, a book, a layer for ice cold A/C, chilly evenings or a rain jacket for the unexpected storm.
It has space for a reusable bottle to stay hydrated or a mason jar filled with a cold salad for lunch.
I would say that the Luminary is a sophisticated Daylight Backpack.
If one's EDC has extended must haves: a big laptop; a full lunch and some snacks; a pretty big reusable beverage holder; files; lots of cords, portable batteries and USB drives and a warm/waterproof layer that one has to carry, the S19 is much better suited for that.