Comment on: 'Does an atom interferometer test the gravitational redshift at the Compton frequency?'

We show that Wolf et al's analysis (2011 Class. Quantum Grav. 28 145017) does not support their conclusions, in particular that there is 'no redshift effect' in atom interferometers except in inconsistent dual-Lagrangian formalisms. Wolf et al misapply both Schiff's conjecture and the results of their own analysis when they conclude that atom interferometers are tests of the weak equivalence principle which only become redshift tests if Schiff's conjecture is invalid. Atom interferometers are direct redshift tests in any formalism. (comment)