Forgot to add a couple of things - at lunch I sorted out how to carry the bag as a regular backpack and to keep the straps from slipping (at least it's working right now). I'm temporarily using 4 rubber bands, but if this continues to work, I'll work something out with velcro. I still can't use the hip belt with the shoulder straps as a regular backpack, the straps are still too long for that. However, it worked fine without it.
While I always knew that you could carry much more when the weight is spread across two shoulder straps, but I don't think I realized how much more comfortable it is that way.
The interior of the bag can be accessed from either side. I think they designed the bags this way so that you can choose which shoulder to carry it on when used as a sling bag. However, it also adds flexibility for arranging things in the bag - I have two lenses that are in the bag but can only be accessed by swinging the bag to the other side, one in the center division "under" the camera with a lens mounted, and the other in the upper division, "under" two other lenses. I really am amazed at how well thought out these bags are.