Is it possible to store (and recall) the state of the mixer as a kind of preset? The goal is to compare different settings of fader positions, pannings, enabled/disabled plugins, maybe even certain plugin settings by switching between these states for an A/B like comparison?
There is currently no such thing as a mixer-only scene. However, you can save snapshots which are “entire session” snapshots (they will include edits as well). See the top level Session menu item. You cannot trivially A/B them (reloading each snapshot is not instantaneous … though if you want it to include plugins, it never could be).