I have no axe to grind in this discussion one way or the other and made my principle point in the opening post. But I must take exception to the contention that the results of the comparison do not provide useful insight. Let me summarize my understanding of the basic argument that the results prove nothing. First, the player is not familiar with the instrument, that it takes months and long hours of practice and familiarization to acquaint oneself with the instrument before optimal musical realization could be expected. Second, that each instrument, even from the same maker, is unique and that some are more suited for certain musical performance than others. In fact some are better than others even from the same maker. Finally there are the artists themselves, and what they need or want in terms of feel and so on from their preferred instrument. For these reasons, it is argued that simply picking up an instrument and playing it for an hour or so in comparison to another proves nothing. Have I got that right? If so, then it should be obvious, without need to refute the validity of any of those points, they would be equally valid for both instruments and for all participants. That is, for both the performers and for the audience. So, if the initial impression is that the new violins out performed to old ones in general for all concerned after only an hour or so of play, that it could be reasonably assumed that the new violins would also out perform the older ones, but by an even wider margin, after months of familiarization.
That this evaluation is subjective and not measurable is axiomatic. Music is subjective and there is much that we don't know and can't measure at the current state of the art. That does not mean that differences in sonics cannot be discerned by music lovers of all ages and abilities.