I use +21/+9 for all mountain. I've been riding this for over 10 years, and I've been riding a forward stance for 15 years. Not sure what the width is, as I usually go one setting out from the inner most holes and it's always worked great.
This past week was the first time I went past 0 on my rear binding. My new park set up is +15/-9. I had to go out to the garage to look, because I wasn't sure. When i set them up, I didn't really pay attention to angles, I just set them to what felt right. I'm surprised, I would have thought my rear was at least a -12. It was a lot different, and I really had to change my style. I don't know how people can ride all mountain duck, you guys are nuts!