I don’t think that a Time-Coherent loudspeaker system has necessary a better sound and image reproduction then a less (but still kind of “good”) Time-Co. Loudspeaker. But please do not miss understand me, of course is not something bad if we have it but probably we will not really hear the differences, I think our ears and senses are really sophisticated and they are able to “correct”, without any problem, this kind of smaller “sound reproductions shifts/mistakes”. The Time-Co. loudspeaker is the one that will show a great Step Response with just mainly one (or almost) peak but in the vast majority of Loudspeakers in the market (also the most of those considered as “masterpieces”) is not like this. Please check these 2 very interesting articles on this matter to get a much wider view on this topic then my simple writing here. I am sure you will find them very useful:

Have a great reading!!!