It depends on the size of diaphragms a.o.
Several systems at Munich featured BMS drivers, among which the Thrax Audio Gaida.
The sound of those coaxial 459.. drivers is (sometimes) perceived as less natural, with a 'plastic' shimmer, which may be noticeable with vocals and acoustic instruments. This is usually more apparent with bigger drivers.
Metal diaphragms are hard to beat when it comes to reproducing cymbals and other metal (snare) instruments.
Soft (ketone) polymer diaphragms (as used by Faital Pro a.o.) tend to sound 'forgiving', which many people like, but which may be
too much of a good thing for larger diaphragms.
However, there are no absolutes in this regard (as well) and personal preferences may vary.