well regardless, i'm sure we answered the OP's questions. But with Class D, i still say you really need to pay attention more so than Class A or A/B, to exactly what your buying. They are a more difficult design and therefor needs some buyer beware.
There are also a ton of marketing gimmicks to read into. Plus different manufactures use different methods, what to me seems to be the same outcome, like Class B/D, G/H or H or Class T. Or even the newer methods of using higher efficient Class A/B using single rail caps to boost the voltage and therefor power to enable smaller applications with large power outputs and still yields upwards of 75% +/- efficiency