After much deliberation (re: should I spend a lot of money on a backpack vs. it's an investment) I bought a S19. For someone who is 5', it fits me perfectly (and I'm kicking myself for all the time I spent on Zappos and REI looking at bags and trying them on). Anyhow, it's coming with me to London as my personal bag and I haven't even left the airport yet and it's generating compliments already! (I've gotten several "Oh, you're so organized as I've had to get various things out).
I have to say that the bottom pocket plus a 3D clear organizer cube on a strap is absolute genius.