Transmission Line Bass

As a long time proponent of good bass without subs, I like tinkering with different ways of approching the age old problem of recreating all energy below 100Hz.
Seriously, if you look at loudspeaker responses, everything seems goes to hell just below that point, swinging wildly in output response, almost independent of many of the typical factors that would be indicators of performance.
So, the question.
Who among us has had extensive Transmission Line Bass Experience in listening, (like me with the IMF's in days gone by, with Bud Fried being a wonderful mentor to me).
In Jim Thiel's lab, one time he told me 'candidly' that Transmission Line Designs 'in theory' don't work. (Another discussion for another time). But he, like me was a bass freak of the first order, loving a rich full bottom end, hence some of his equalized designs early on. They were an all out attempt to bend the laws of physics.
So, what do we think of Transmission Line bass--so, if you're familiar with the sonics though actual listening, and can express first hand opinions let us hear your impressions of the differences between ported, passive radiators and transmission.

Thanks in advance...

Larry