Here's a tip from the trenches - the 3 programmable buttons near the joy stick:
#1 - Auto bass OFF
#2 - 1-5 acc tracks OFF
#3 - Leslie fast/slow

This allows so much freedom - you can instantly thin out a track or substitute a manual bass line without any fuss, and jump back in very quickly! Try it!
One of Korg's best access buttons is the ability to switch from LH arranger to RH in an instant WITHOUT going into menus. If I want the harmonies to follow my RIGHT hand - I just tell the arranger that I'm using RH trigger, and then I shut off the appropriate voices - in my case, usually all auto stuff, so I can use the LH bass, RH chords (MY chords), and still get the vocal harmony that follows my chording hand.