I have a suggestion for an accessory.
I just got the US30 and love it. I use it for commuting and it's become my trunk. I loosen the four straps and unhook and remove the bag. I'll then either attach the shoulder strap or just grab it by the center strap that goes over the roll top section. The problem with that strap is that it's oriented in the wrong way. It turns your wrist sideways.
There are the two D rings at the top (or bottom) and what would be perfect would be a handle. It could be super simple, just a single strap with Velcro™ for attachment. But I'd let the Kriega guys figure out the final engineering.