Stephen,
If you search the Web a you'll find a handful of very smart folks have already put a lot of effort into deconstructing and understanding Yamaha styles. Look at sites like psrtutorial.com. Google names like Jorgen Sorensen, Michael Bedesem, Ocenenko Evgeny, Paul Tumelty, not to mention posts by Dan who wrote and supports vArranger. I forget where I downloaded it from, but in my reference folder I have a 30+ page document that describes the Yamaha Style File Format (SFF), at least pre-SFF2 when they introduced guitar mode.) It explains how to edit the CASM to get Yamaha styles to behave like Korg and Roland (where you can have different pattern variations for different chord types.)

I agree with the poster who encouraged you to work with the earlier styles first. I will further advise you to download all of the manuals for the QY-700 sequencer, PSR-730, and PSR-8000. Look at stuff from around 1995 when SFF and XF/XG were new technologies. It seems that back then, Yamaha put more detail in the manuals, perhaps in an effort to allow users to fully understand the new style format and get the most out of it. If you do the research that I'm suggesting (and TEST your hypotheses on an actual machine) you'll know as much about SFF, NTT, NTR as anyone here.

Good luck and we would love you to share your findings, sincerely,
Ted