Pro Tools would benefit from having recallable mix "scenes" (or Automation parameter scenes) available within a single session. Users should be able to generate and store an arbitrary number of recallable scenes. When a scene is recalled, the faders, pans, send, plug-in settings/bypass, etc all change to their saved vales. This feature can allow for a number of significant workflow improvements.
It would allow:
-Alternate mixes to be recalled instantly for A/B purposes
-Alternate effect chain comparisons
-Alternate temporary mix states for editing operations, for example: While comping a vocal performance, you could recall a mix scene where vocal levels are increased, and other track decreased.
-Save mix scenes to denote what date the mix was made, and/or other circumstances (What studio the mix was made in, which reference monitors, other factors)