I think many people disregard the effect of the source material's frequency/harmonic/dynamic content when referring to SET vs solid state amplifiers. If the content is limited to more of the mid-range frequencies, has limited dynamics and isn't too complex, it can sound good for reproduction. Driven hard, they compress dynamics, clip and lose their fidelity. However, as a design for producing the sounds of electric guitars on recordings, they sound very good to those of us who would use them (although I still prefer push-pull Class AB for that). Most other people would just roll their eyes and walk away, muttering.
It would be interesting to use an amp like this on a desktop system, IMO.
Why is it that some say it's important that we have detailed specs for speakers, but when an amplifier's specs are terrible when compared with a Solid State amplifiers, some say "don't worry about the specs, just listen to the music"?