Another factor you should look into is that ATC don't put a lot of emphasis on cabinet resonance control.
The freestanding set of ATC's that Pink Floyd use have additional bracing inside. Many studios soffit mount them.
What really bothers me is ATC's treble extension
Indeed ATC focus on the range up to 12 KHz with soft dome tweeter (preferring damped type drivers over rigid types) - this design definitely rolls off earlier than some metal domes like the Be dome or designs with super-tweeter.