cd318,
Interesting list.
The main problem I see is the subjectivity involved. If we surveyed everyone here we'd see a huge variety of speakers being used, and I doubt many people would say "My speakers don't do instrumental timbre well." In other words, that list could be expanded to the point it's not terribly useful.
That's not to say that I think that it's just entirely subjective whether a system produces accurate timbre, or accurate sound in general. In principle, it seems to me, blind tests could be set up with, say, live vs reproduced sound and a large enough sample size of participants, and tests, over time could produce results showing some speakers produce sound closer to indistinguishable from live (and hence good timbre) than others.
But as that isn't happening much at all, we are left to what measurements can tell us, and ultimately our own impressions.