There were some interesting things that came out of this today.

For low impedance speakers, the extra set of channels most likely makes a very audible difference. But, there are probably very few of those in the world.

The extra set of channels can also power another set of fronts. I'm not sure exactly what the application for that may be. But I've noticed that two sets of fronts sound more full.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated