My suggestion is that the Pro Tools Mixer has Playlists. So for example:
1. You could duplicate a mix, try different things, go off at a tangent etc.
2. Create a new mix. "Zero" the mixer and start again with the option of going back to the original.
3. Move tracks between mixes. For example, duplicate a mix and get a better drum sound, then copy those tracks into the original mix that was otherwise fine.
4. Splice sections from different mixes to create a new mix. Comp a mix in other words.