Lamar indicated at a SM clinic that the Nomad development started with smaller wings, and the first Nomad wing was a 50 pound wing, but it also was not adequate for some types of diving as the wing is not really able to expand to it's full capacity, because, as Rob notes, the wing runs under the harness and bungees, and the wing is tabbed down to control the shape and to prevent it from tacoing. The end result was a 60 pound wing on the Nomad that in practice is probably only giving a maximum of 40-50 pounds when everything is in place and adjusted.
I do see Peter's point on the question of the large center plate on the Nomad harness. That's an artifact of it growing out of the Transpac harness, but part of it is due to the desire to keep the vertical profile fairly flat. That is accomplished on the Nomad by having a standard shaped wing (evolved from the Trek and Rec wings) and then attaching the lower ends to the waist belt, keeping the front portion under the shoulder staps and using tabs and bungees on the midel portion in addition to the tank bungees holding it down.
Andrew Georgitsis is taking a slightly different approach with his sidemount/monkey diving harness in that the harness is primarily located in the small of the back and is triangle shaped, with the pointy end extending up to a point between the base of the shoulder blades. This keeps the buoyancy located where it is needed.
I have also seen the third prototype from another company (kept nameless at the developer's request) that is also seeking to develop a wing that has the lift biased toward the lower body with no air anywhere near the shoulders. My impression was that the 4th prototype would probably depart from the traditional perimeter design and would also be a bladder along the lines of what AG is doing.
When I bought my Nomad the guy I bought it from threw in a nearly new Rec Wing as well. I placed a very slightly modified Oxycheq travel plate over it and created a "Fauxmad". Same basic idea and given the origin of the Nomad wing, it is a very easy DIY project to complete. But unless you already have a wing, buying a Nomad is probably more cost ffective.
In any case, the harness, wing and bungees operate as a system and any of them impacts the other two and that can lengthen the learning curve if you don't have access to an instructor or mentor. And some issues you just encounter when new items come along. For example, I like ring bungees for carrying tanks fair distances to off the road sinks. But they don't really pull the tanks far enough forward to get the right trim (especially if diving wet) - regardless of where the bands are positioned, so a slight mod is needed to ensure the tanks ride properly.
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Like Rob I have not had issues with dumping a Sorenson inflator modified Nomad in feet up positions, and I have tried to aggravate the situation in a dry suit. In part it is where the tanks are located. However a large part of it is also due to the wing being under pressure from the bungees, tabs and tank bungees, so that regardless of where he inflator is located, it dumps gas when the button is pushed on the inflator dump or when the dump cord is activated. By the time the pressure in the wing is too low to dump gas, excess lift is just not a problem