To add clarity, concentric is a subset of coaxial. In other words, all concentric drivers are coaxial but not all coaxial drivers are concentric. @erik_squires Pardon the presumption; you are probably referencing most designs intended for the hifi home user, of which most (if not all) are concentric.
I heard a few designs at audio shows as well as listened critically (TAD micro) while evaluating two amplifiers for purchase. Having experienced music through quality concentrics, my opinion is that a quality design well executed in all parameters sounds great.......concentric drivers or not. The theoretical advantages of concentric drivers notwithstanding, there are probably a number of other design variables that bear more weight (at this point) on how a loudspeaker "sounds" to each person.