Dali Concepts use fabric domes. All else being equal, I don't think they can be "brighter" than those w/ metal tweets.
This comment gives me the impression that the tweeter material
determines the speaker's overall sound character
(that is, whether it is 'bright' or 'warm').
You are essentially saying it is
impossible for speakers with fabric domes
to sound any 'brighter' than those with metal dome tweeters.
I think this generalization is wrong.
Bose acoustimass speakers are made of cheap Manila hemp
and don't have dedicated tweeters. Do you honestly think they
do not sound brighter than say, Wharfedales or B&W's?
The characteristic 'brightness' of a speaker is not a mere function
of the tweeter material it is made of. It is a function of the whole package
of which the midrange and bass drivers also play a crucial role.
In fact, the midrange and bass reproduction can have more impact
on the overall speaker sound (whether 'bright' or 'warm') than the
tweeters alone. Remember that the tweeter only produces a narrow
range of frequencies compared to the frequencies produced by
the bass and midrange drivers. Tweeters also produce only a small
fraction of the SPL levels produced by the midrange and bass drivers
which makes the bass and midrange drivers (particularly the midrange)
more controlling of the overall tonal character of the whole speaker package
than the tweeters alone.