We first compare different versions of SAPT0(KS), meaning second-order perturbation theory with various SCF methods to generate the monomer wavefunctions. We use error statistics versus CCSD(T)/CBS interaction energies, for the S66 data set, as a means to evaluate different approaches. Figure summarizes results for four different SCF functionals and two basis sets. Results in Fig. (a) use the jun-cc-pVDZ basis set that is found to be a good compromise for SAPT0(HF). This basis is a proper subset of aug-cc-pVDZ, eliminating diffuse functions on hydrogen along with the highest angular momentum set of diffuse functions on other atoms. Its success for SAPT0(HF) calculations (and for MP2) rests on error cancellation, as is evident from the fact that both the MAEs and the maximum errors increase when aug-cc-pVTZ is used instead [Fig. 12(b)]. Nevertheless, MAEs are no larger than 1.1 kcal/mol for each of the traditional subsets of S66 including hydrogen-bonded dimers, dispersion-dominated complexes, and dimers with mixed influence interactions. Interestingly, opposite basis-set behavior is obtained with and without the δHF correction. At the SAPT0(HF)/jun-cc-pVDZ level, the errors for hydrogen-bonded dimers are unacceptably large (up to 6 kcal/mol) when this correction is omitted, yet for SAPT0(HF)/aug-cc-pVTZ calculations the δHF correction has little statistical effect. This is a curious result that went unnoticed in comprehensive benchmarking of various levels of SAPT approximations, because the δHF correction was always included in the SAPT0 level. This observation points to an additional source error cancelation.