Who is right, and who is wrong?
I disagree with your leading premise that there is a “right vs wrong”.
Perhaps if a single driver can do the speed of treble down to bass that can move enough air would be ideal, but doesn’t exist. Therefore tradeoffs are inevitable- there is no perfect speaker design.
Also, there’s “higher efficiency” that’s seems to be ignored when comparing Guader offerings to high efficiency Voxative and Zu, the latter which can run on very low powered amplifiers down to SET tubes Sonics.
I’m a fan of Gauder’s products indicating excellent engineering, but I do not reach farther in declaring them “the” global spokesman for what is best/right/wrong.