Hi Dralion,
it's a function they created years ago, I'd sort of forgotten all about it. Handy also because it allows you to use your sts settings with harmony for R/H. I'm not too wrapped use the harmonized voices in BIAB itself. For me it's handy for practice, as my playing hasn't improved over the years. haahaa
Don't know what version of BIAB you have, but do you use the Real Tracks? Interesting replacing 1 or 2 of the korg style tracks with a real track . Great how it can all sync together.
I'm going to have to start making notes of which real tracks go well with which style.
So much nicer having a real strumming guitar playing , rather than a 2 bar loop in my converted styles just adds a bit of variety to the song.
I also use BIAB with my Korg microArranger. I use BIAB chord output to play styles on the microArranger, especially songs with Jazz chords that are very difficult to play left hand voicing on the microArranger due to its small (and short) keys.