George,
Measurements mean very little......you must listen, listen and listen some more.....for reality. Of course, really bad measurements are usually detrimental......however, what constitutes bad measurements? You would have to listen to determine that.
I think GaNs will make class D better (everything else being the same). However, we are in the infancy of their use. Every GaN and every mosfet based class D amp will sound different as everything you do makes a difference sonically. We have years of perfecting yet to come.
These first GaN amps are just the tip of the iceberg. We will see relatively inexpensive GaN amps that blow these expensive first offerings away......no doubt.
Cannot wait for Worldwidewholesales to finally tell us their comparisons of all these GaN and non GaN (mosfet) class D amps.