I have a hip belt pocket that is very close in size to the Large Gossamer. I use a small from MLD for my camera.
However, I no longer carry my camera (Canon Powershot A540, a small digital) on the hip belt. When I remove a pack, the hip belt, especially if it has the weight of a camera, tends to swing around and could bang into the ground. Sometimes I just forgot about the camera being attached there. Now I carry the camera in a pouch attached to the shoulder strap. It fits in a smaller bag, (LowePro Z 5) but to make it easier to get in and out, I use the LowePro Z 20.
Check OR, too. They make a smaller shoulder strap bag with the attachments going the right way, horizontal, not vertical.
If the Gossamer shoulder attachments fits your camera, go with it.