Surely the most important thing is not the quality (the engineering quality, presumably) but what turns you on the most AFTER experiencing other options.
Specifications and physics are one thing, but experience is second to none. Obviously one needs academic guidance to ensure compatibility, but without experience how can you eschew something out of hand because or conflicting statistics?
Apart from the obvious advantages (as against about the only vague disadvantage; that of rigidity), I'd say the sonic scenario is one of taste.
As I've mentioned before, this discussion about 12" versus 9" (or any other length) is surely ONLY apposite to those who can avail themselves of the choice. From what I've learned over the last few months, SME's decks are prescribed for one length arm only except in the case of one model in each of the 20 and 30 range; and that at a heck of a price addition. Happy to be informed otherwise, of course.