Dealing with a MIDI guitar controller, and two signals (electric + piezo) from same guitar, I see that the use of the return and alternative input is a little tricky.
If you connect the MIDI controller or expander to the return + aux you need to insert an Fx loop stomp if you want to mute or mix the ouputs. But, when you set the FxLoop to off, this lead to the input signal reappearing, as the fx loop was not present.
Therefore we cannot use a remote controller switch to select which sound we want to ear in the Main out (electric signal coming pre-Fx Loop or acoustic/expander post Fx Loop. The only way is using a MIDI control change to drive the Mix parameter of the FxLoop, but the Remote doesn't send MIDI, at the moment.
[edit] Not secondary, any signal inserted in an FX Loop is affected by the CAB simulation.
Another scenario is to mix a piezo signal. Inserting it in an FX loop will introduce unwanted CAB sim.
It would be preferable that (when no FXLoop are present in the chain) the level of the AUX input was stored in a per-rig parameter rather than a global Output parameter.
Thanks.