I ended up going with the Empire Builder, it arrived today. I'm pretty impressed. These are nice bags.
The bag was a little heavier than I expected when empty. The size looks about perfect for my overpacking on trips, and in fact is a bit smaller than I expected so I can see it getting some daily use to the office as well.
Messenger slinging seems like it will be fine for general commuting/traveling.
Thanks for the advice.