Sorry but I am not buying it. Since this design employs dual woofers, they either need dual lines or have a single entry point with an exit equidistant from the "woofers". This is not apparent in this design and the claims that their design can extend bass below what a ported design can do are dubious at best. In order to reach down in the 40Hz range, the path length would have to be 7 feet long!
Also looking over the impedance plot, you can see a saddle point right at the tuning frequency. I would expect a flatter impedance curve for a true TL design. At the very best it is appears to be an under stuffed TL design or a hybrid/quasi TL design that also incorporates a tuned vent