phase coherence made other anomalies much more obvious, requiring solutions to problems that would have remained invisible in normal phase-compromised systems.Yes, I would agree with this. I also think first order, time-phase coherent design has a "special sound" that cannot be found in other types of design as I have said so in some of my previous posts.
Also, FYI, the studies done in my previous post (said link) was not necessarily done using first order speaker. I won't go into much detail, but basically they use a front end DSP software to linearize the phase to make the speaker 0 phase even if the speakers were LR2 or LR4. I suppose the difference would be more obviously if the studies were done using purely first order speakers.