In the past, when I started mixing I would save my initial mix as [Name of Song][Date project started][Revision][Mix #]. I would then export the mix as a wave file, and then import it into a mastering template with other songs to be mastered. I believe other members have a similar work flow.
Mix Recall eliminates the need to save a whole project with a different mix number as I can save a different mix right in one project, give the export the same name with new mix number, and put it into the master template.
Mix Recall is fine if you want to just compare mixes one at a time. Sometimes though I like to hear real time differences, i.e. real fast A/B comparison. For example different eqs, with difference console emulators s-type,etc. Personally I can't hear a difference if I use Mix Recall to do this function since it takes a few seconds to load in a different mix. By then I forgot what the first mix sounded like. (It's a feature associated with older age...)
What I do is in the Mastering Project, if I want to A/B two mixes, I mute one and use the group function to tie the two mix mutes together. This way if I mute the non-muted mix, it mutes and the other mix unmutes. Now I have instant A/B comparison.
I also send each mix to a separate bus, so I can add a final eq, iZotope secret sauces, etc. The Group Mute function can be used here also.
Sorry if this is common knowledge on this forum, but I'm waiting for some guests to arrive, and this gives me a chance to keep proficient at touch typing. and maybe this post might help someone.
Walt