There is really no agreement about accessories, pouches, bungie cords, hip belts, etc with regard to the packs. There is a large discrepency in listed weights, sometimes as much as an ounce or two, since they don't make all the packs identically. There are several methodes: an average taken for 20 or so packs, the first one off a line, individual component weights, and so on. Nor is there full agreement about what should be included with packs, other than having a main body. Some people like hip belts, others don't use them and remove them...the user often decides what is included by adding a shoulder pouch or attaching water bottles to the shoulder harness, or, by simply removing all excess weight(straps, buckles, excess cordage, hip belts, etc.) It would be nice to be able to compare them.
But, I don't believe it is all that important. A pack that is comfortable should ALWAYS be the best determining factor. I find that even SUL packs (like the Murmur, Zero and others) can be brought up to about a pound, or, reduced to about 5oz (or less,) depending on what the user wants/needs.