There are subtle differences between Class D amps, usually dealing with higher sampling rate and analog reconstruction of the discretized signal. Atleast that's what my understanding is.
But in all seriousness... have you heard a 3kw car audio system before???
At 3kw, you won't be able to tell an SQ difference... Even at 1kw, it's tough to tell much difference, until you get to clipping.
As is repeated over and over on this forum, it's all about the box. Select a power range, and get quality equipment for that... then it's 90% box size, tuning, and build quality.
Edit: the THD probably is higher on this, compared to other amps. If you look at the guts, it's really simple... which usually means there isn't much control circuitry, filtering, etc. I also haven't tested this amp at higher frequencies, but iirc, the manual it goes from 16 - 180 Hz...