The only other TL speaker I've heard was a Meadlowlark Kestrel a number of years ago. Just like you, I wasn't at all impressed. It lacked bass, and it cost about $2500 if I remember correctly.
That may be why I was so impressed with the Songtowers. I also have a pair of bookshelf 2-way speakers made with the same two drivers. It is in a small vented cabinet. (It's a DIY design, made by Dennis Murphy, see CAOW1 below in my signature line.) They produce bass down to about 50 Hz, and then rapidly drop below that. When I first heard ths Songtowers, Dennis used an electronic tone generator to show that they could rattle windows and doors in his house at 38 Hz.
Here is the frequency response curve from 200 to 20,000 Hz.
Its as flat as I've ever seen. The crossover frequency is about 2600 Hz.
Jim Salk is located just oustide of Detroit, in Oakland, Michigan. That's not too far away for you.