Bose also uses transmission line designs and holds several patents on them. The little Wave Radio uses a transmission line. BTW, transmission line applies/impacts typically only the low end portion of the speaker- not the midrange or above (other than its bass output is in phase with the overall system). So like bass reflex or passive LF drivers or other boosting strategies, they attempt to reduce the normal 12 dB per octave low end roll off you get with a sealed box. Since most home hi fi speakers need to be smaller, the port helps us get low end that would otherwise not be possible from that size [sealed] box. The trade off/cost is usually a more rapid roll off of bass after the designed "boost" point of the port or passive driver, usually a roll off of 24dB per octave (that's rapid). But compared to the 12dB per octave sealed box, it is possible you could get more deep bass out of a sealed box system than a ported system, especially if you are willing to go larger. So the "boost" from all these different strategies always has a price, the price is some other negative that you cannot avoid if you want the boost.
As the engineers at ATC constantly explain to me, everything in speaker design is a trade off. You can't get "this" without "that".
These deeper performance values are good to know when you are speaker shopping. It's what usually differentiates one company over another, the choices they make and the price of those choices; how do these choices align with your choices? It's good to know what you value, which is to my way of thinking, what a speaker demo is all about. If you value low distortion, you usually also avoid bass boosting strategies because they generally increase distortion. If you value bass, maybe the ported/transmission line speaker is the right idea? Depends on what the rest of the system sounds like but porting is one low cost way manufacturers deliver "more bass". What if you have a small room? Deep bass is not supported in a small 10x15 room, wavelengths are too long. A sealed box speaker may be perfect for you after all since you can't pump a lot of bass into the room anyway- even if the speaker will do it.
Brad
