Those are some good tips from Andrew Newton. By leaving my neg. mix numbers at 0 on mixes 2 and 3, I basically just achieved the same thing he did with the offset. I didn't need/want spoilerons, so everything just went to a neutral configuration if the knob was at the mid point or below. You do need the offset if you're moving it onto the switch, though.
As he notes, you can't feel the center position on those knobs, so it would be somewhat tricky to fly the way he initially programs it. Hence the new knobs I made so I can feel the position.