Agreed. And I think there's a lesson here -- even if you are done with what you are doing on a BIAB song, freeze all tracks as a final step (or save a copy with everything frozen). You never know what additional functionality or quality or whatever PG Music will come up with down the line, and you want to be sure that your prior efforts can to the greatest extent utilize them in the future. And also label that file in some manner that indicates it is the final, fully-frozen version. Maybe others do that already; I don't consistently but I will.
Beyond that, and just thinking out loud, I wonder if there is a way to somehow isolate separate frozen tracks in some kind of separate/independent song sub-file so you could better pick and choose and archive them for best access. Presently, it is hard to find particular frozen tracks amidst fifty sequentially-named iterations of a song with selective freezings. Basically, I'd like a way to cherry-pick the frozen piano on iteration 8, the frozen guitar on 23, etc. To date, I achieve that to a degree through the exported WAV files, but the WAV file could not be improved upon through subsequent BIAB improvements as we have discussed here -- you need the frozen tracks of the song file(s). Just something to think about.

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