  We critically review the validity of heavy-quark spin and flavor symmetries
in heavy-light decay constants, form factors and effective couplings obtained
within a nonperturbative framework, the ingredients of which are all motivated
by Dyson-Schwinger equations studies of QCD. Along the way, we make new
predictions for two effective nonphysical couplings: g_{DsDK} = 24.1+2.5/-1.6
and g_{BsBK} = 33.3+4.0/-3.7.
