I wish that this command would honor the Pickfirst selection. Now when a Featureline is selected and the Context menu is shown, selecting the QuickElevationEditor starts the command, but if the command was last used with a F/L in a different site than the one the selected F/L is in then you are left wondering why the command isn't letting you edit the F/L you had started with. Enterimg S, then choosing a site will change the site but often I'm not sure which site I'm currently looking for. This command should auto-switch to the Site which holds the selected F/L.
Yes, I find this behaviour in a few civil 3d commands and it is quite painful as it is not the expected behaviour for a command in autocad.