You likely wouldn't.

Of course anyone can feel free to correct me, but in my understanding;

BiaB used to use a different algorithm (method) to time stretch and pitch shift the Realtracks to make them fit the chords.
With the old way, many systems performed better with this optional choice (some one way some the other).
PGMusic has kept this setting to support the older versions. With the newer versions (and newer computers) it is really not needed. It could probably be phased out now since very few users need it and if they are running the current version most likely do not see any benefit.

Just my thoughts
A weird 'backwards compatibility' feature that they have held on to until now.
Now that it is causing issues it may be time to rethink this strategy, which is possibly what PG meant when he said it would be fixed.

I do not work here, but the benefits are still awesome
Make your sound your own!