My wallet may be in danger this time. I found the Deuter Aviant 40 liter Duffel online at Enwild.com and on Amazon (on Amazon - you have to click on the 60 liter bag, then select the 40 liter bag). This is the bag I have been looking for. There is a 35 liter bag. But, it's not clear on the website that it can be used backpack style. Only looks shoulder strap and grab handle style.
I like that Deuter is more discreet in its branding/labeling. Now, instead of looking like an American tourist - I can look like a German tourist.