Follow up: I bought this bag from performancebike.com and it was great at first! I was pleased with the design and it mounted and dismounted easily onto and off of my delta rack. It then began to rip on the inside liner. It probably never would have started doing this if I hadn't picked up the bag fully loaded with the main cover unbuckled. This allowed the weight to supported by the weak inner lining of the bag. If you plan on lifting the bag without closing it all the way then this bag will probably rip, otherwise it seemed like it could hold up without a problem. Otherwise I was pleased with it and I wish I didn't have to give it up.
I bought a Carradice Bike Bureau for $80 more that I have high expectations for.