  Flavor symmetries successfully explain lepton and quark masses and mixings
yet it is usually hard to distinguish different models that predict the same
mixing angles. Further experimental input could be available, if the agents of
flavor breaking are sufficiently low in mass and detectable or if new physics
with non-trivial flavor charges is sufficiently low in mass and detectable. The
recent hint for lepton-nonuniversality in the ratio of branching fractions $B
\to K \mu \mu$ over $B \to K e e$, $R_K$, suggests the latter, at least for
indirect detection via rare decays. We demonstrate the discriminating power of
the rare decay data on flavor model building taking into account viable
leptonic mixings and show how correlations with other observables exist in
leptoquark models. We give expectations for branching ratios $B \to K \ell
\ell^\prime, B_{(s)} \to \ell \ell^\prime$ and $\ell \to \ell^\prime \gamma$,
and Higgs decays $h \to \ell \ell^\prime$.
