I agree, I don't think it's better or different. What sticks in my mind is that I think its a rate problem. Meaning audible bass volume is relative to volume

I agree, I don't think it's better or different. What sticks in my mind is that I think its a rate problem. Meaning audible bass volume is relative to volume of air displaced. It's like when we design pumps. There are positive displacement pumps, flow equals stroke volume times stroke rate. Stroke rate is frequency, stroke volume is stroke times surface area. So bigger subwoofer diameter equals bigger surface area. You can also increase the stroke. Anyway, that all integrates to flow. We also have rotary pumps like centrifugal and axial flow pumps. With those flow is a function of rpm and pressure gradient across the pump. (Pressure gradient across the pump is not a factor in positive displacement pumps). To me this is why they needed such a large chamber. Below a certain size they were sucking down the Pressure too much. Also it's much flow that the pressure gradients ar such that it limits its frequency response to 10 hz or so. All this to say, I think the mistake was simple. They said existing subwoofers are 12" so let's make a 12" rotary sub. I think they should have said a 12" sub has a volumetric displacement rate (diameter times stroke times frequency) of X mm^3/s and if we design a rotary sub to have that same volumetric displacement what are it's dimensions. It would be far less than 12", likely 2" or so, and very compact yet powerful. That form would also dramatically change its frequency response and performance. This is what I've been wanting to build for years, a 2" rotary sub with a very powerful fan.