Yes, indeed, I happened to notice this when I was just playing chords in my Left Hand!
So, I experimented with those settings, and actually, I like using the "Narrow" setting.
It's a subtle change, but I do hear a little better separation between 2 Chorus voices, instead of just leaving it "Off".
By the way, here's a little tip for everyone, in case you may not know about adding notes to a .PDF file.
I copy and paste these comments into Adobe Acrobat Reader, and build up the SX-900 Reference pdf!
In this case, on page 12, just right-click where you would like it to appear, and choose "Add Sticky Note", works great.
You could Edit the PDF, I suppose, but it's really easy to just add these comments instead.
Regards, Jerry