We assess the performance of ECI by computing absorption spectra of two multichromophoric systems. The first system, a metal-free guanine quadruplex, has the chromophores connected via hydrogen bonds (a supramolecular complex). The second system, a guanine quadruplex with a central Mg 2+ cation, additionally exhibits metalligand bonds between some chromophores. It is shown that the accuracy of ECI strongly depends on the chosen embedding charges and ECI expansion. The most accurate combinations-ECIS or ECISD with EHF embedding-yielded spectra that qualitatively and quantitatively agree with full-system direct calculations, with RMSDs of the excitation energies around 20 meV or 100 meV, respectively, for the first and second test system. We also show that ECISD based on CIS site state calculations can predict states of dominant MLE character that would be inaccessible in a full-system CIS calculation.