Our findings can be summarized as follows. For ethylene, we have found that the PES around a minimum energy conical intersection obtained with XMS and XDW is smooth, while uncompromising artifacts were observed for RMS. As already documented in previous works, MS failed in this respect. Smoothness is observed in the case of XMS-RASPT2, while the qualitative characterization of the conical intersection strongly depends on the parametrization of the RAS. Vertical transition energies for the benzene molecule computed with several flavors of MRPT vary within the expected accuracy for this family of approximations, such that no definitive conclusion can be made in favor of any variant. Returning to ethylene, now looking at S 0 → S 1 excitation energies at the Franck-Condon structure, we observed that XMS and RMS are less sensitive to the number of states included as compared to XDW. On the other hand, for the relative energies to the MECI, XMS and XDW are more sensitive to N state than RMS. In the case of dioxetanone it was found that CASPT2 molecular structures may be qualitatively different from those obtained with CASSCF, and could induce different relative energies between stationary points. Additionally, the (16e,13o) active space applied to this molecular system was utilized as a reference in assessing the appropriateness of smaller complete and restricted active spaces. For the case considered here, it is relatively straightforward to construct compacter CASs which provide consistent results with the reference, whereas this is a much more delicate task in the case of RASs.