  Estimates of the light hadron masses, decay constants and couplings in
AdS/QCD models are generally more accurate than should have been expected.
Certain predictions based on the AdS/CFT correspondence, such as the ratio of
the equilibrium viscosity to entropy density, are universal and therefore
provide firm experimental tests of these models. Other observables, while not
completely universal, may be relatively insensitive to model details. We
calculate the dependence of a number of low-energy hadronic observables on
details of the hard-wall AdS/QCD model. In particular, we vary the infrared
boundary conditions, the 5D gauge coupling, and the mass of the field
responsible for chiral symmetry breaking, while holding fixed a small number of
observables. We also find a generalized Gell-Mann-Oakes-Renner relation which
helps to justify the identification of model parameters with the product of
physical quark mass and chiral condensate as per the AdS/CFT correspondence.
