Most of the "streamlining" that is suggested has more to do with how it looks than anything else. There are two major fallacies, both stemming from a lack of actual testing. The first I have not tested either, that is clipping your spg, which I object to on other grounds, namely whenever you create a closed circle with your gear you are raising the ante on entanglement, I put my spg under my tank in the small of my back with no clip or securing ... it tends to stay there, except when I pull it out to look at it. The second (and in this case actually demonstrable fallacy) is the idea that all BP/Ws have less drag than any vest. I prefer BP/Ws over vests, for a number of other reasons, but that's for a different thread. Many years ago Steve Paulet and Dave Mclean (both used to be here on SB, they show up once in a while now but you can find them on FaceBook if you want details) did a seminal study of BC drag by towing divers and a dressed manikin in a ship hull tow tank that was instrumented to record the force needed to move through the water. This study included a prototype for what became the SeaQuest ADV as well as the Watergill AT-pac (an early BP/W very similar to modern ones but with a plastic backpack rather than a metal plate, it could be equipped with a fiberglass fairing and was towed with and without its fairing) the results were not what you'd expect. The ADV did best, and the BP/W without the fairing did not do as well, with the fairing it was even worse. I do not know that "modern" BP/Ws would fare the same, just pointing out that there a a lot of noise on the subject and very little hard data.