  Two important sources of systematic errors in lattice QCD calculations of
radiative leptonic decays are unwanted exponentials in the sum over
intermediate states and unwanted excited states created by the meson
interpolating field. Performing the calculation using a 3d sequential
propagator allows for better control over the systematic uncertainties from
intermediate states, while using a 4d sequential propagator allows for better
control over the systematic uncertainties from excited states. We calculate
form factors using both methods and compare how reliably each controls these
systematic errors. We also employ a hybrid approach involving global fits to
data from both methods.
