Wiring as a full fader allows you to drive the first stage into clipping yet still maintain full output level control. Wiring as a 6dB trim allows fine adjustment of gain between switch settings.
i just figured out that the N72 is the only module to offer the trim knob to be used as a fader (just got 2 J99's and 2 A12's). is there any way to wire these up as faders instead of trim?