Just on first inspection, I'm not impressed. The subwoofer design I saw is not a transmission line, but more properly an acoustic labyrinth I believe. They also discus a 1/12 wave Transmission Line and a Port Tube. None of my research has shown a port tube in use with transmission lines. That said, a Mass Loaded TL has what is most similar to a "port" in that the terminus of the line is restricted by a smaller opening... otherwise, the end of the line should terminate in a ratio based on the Sd of the driver.
Beyond that, I did not pursue any testing results, if any are even available.
*shrugs