As one can extract from the discussion of the individual entries, the choice of dimensions used for the partial anharmonic corrections wildly varied. The water-benzene dimer (a system which was not featured in this challenge) was recently studied by Felker and Bačić. In their study they obtained a striking agreement between the symmetric OH shift calculated from an adapted PES considering only the water degrees of freedom and a larger 9 dimensional PES whereby coupling to large amplitude motions was included. However, the agreement is found to be precarious, as replacing one of the hydrogens by deuterium (HOD) shows. Deviations rise from under 1 cm -1 to an order of magnitude larger. A more systematic review of the systems featured in HyDRA could be warranted to observe how error compensation is at work from weakly to strongly interacting dimers.