Hmm, I'm curious about the 43 ounce weight for your Circuit.
My large Circuit has all the removable items stripped off, and I am using an ancient ULA hip belt which is smaller than the current version, and it weighs 34.75 ounces. The newer hip belt can't be that much heavier, can it?
(Edit: it's got some custom features that may cut the weight, too, like the drawstring top and the Ohm stretch mesh pocket. Huh, didn't think about that when I ordered it.)