I think the appeal of Transmission lines was (when done properly) was they did not have peaky low end boost as so many short port speakers offered at the same time. There were a lot of crappy cone speakers around when Freid was hot in the late 70s. Really nice extended lows from very small drive units. However, the TL vs port is a bit unfair, like comparing apples to oranges. A transmission line is BIG, and even a long port speaker was much more compact and workable into a room. Most purchasers would not be comparing a TL to the more compact monitor for a host of (non audio) reasons. A Dahlquist DQ10 was easier to work into a room than a big tall wide top of the line Freid..
Brad
Brad