I am having a lot of fun modifying styles to my taste in the Audya. I don't have AJ's expertise, but I have been doing it this way.
1) I always use the "user styles" for editing.
2) If you want to change each variation (intro, ending,etc) select a style ----> hit Style view and change instruments and volumes on each of the style parts. At the end of you editing hit save and don't change the name of the Style.
3) if I want to change a style in a "global" way (no var parts one by one) I select one of the user styles, hit EDIT, change volumes, instruments, octave, add Audio Drums or Live Guitars and when finish with editing I just hit "SAVE" and I save it with a new name. Next I play the style, if I found some things that don't please my taste, I edit it again and keep the same name.
The fun part is that you can edit the same style, do partial changes and save each style modification with a new name, meaning that you can have many variations of the same original style.