Brass reeds don't usually break (at least not the kind you see in
regular organs).  They use brass because it is easily workable, and can
be manipulated to have the correct curve, which is important in voicing
reeds of the kind I mentioned.  However, if you work the reed back and
forth at an extreme angle, it will probably break.

I honestly have no experience with organettes, but I think that the
brass on the reed should be similar.  If the brass is thinner, it just
bends easier.  Again, that is why they use it, because it is easily
workable.  Hopefully this answers the question that was asked.

David Schroth Jr.