I'd never heard of Class-T amps before, either, but some reasearch leads me to believe that they uses some advanced DSP to achieve more accurate waveforms than Class-D amps, while still remaining as firmly in the digital world. It looks like they've been used for a few years in low power applications, and are just now getting to car audio.

I think that there's no disadvantage against Class-D, but still might not be as mellow as a true analog amp, if potentially better than the Class-D. It sounds like if your choice is between a Class-D and a Class-T, that you're more likely to like the sound of the Class-T better.

Also note that the Class-T term is promoted by a single company, Tripath, that developed them, although many other companies seem to be using their technology. The reason I point this out is that it seems to have not (yet?) gotten to the point where multiple companies are making them, which may mean that there might be some infancy to work through before they become truly robust. But I don't know for sure.